"You really want a pet?" Diff says. He can't believe what he's hearing. "We've got a lot of logic to build and the boss keeps mentioning deadlines and I'm supposed to be meeting Zoe in an hour."

Diff grabs a can of canned air, leans back in his chair, and sprays it through his beard so the ends of his Fu Manchu dance. He hopes it makes him look thoughtful instead of annoyed.

"Jack," he says to the face in the monitor, "do we really need to have this conversation now?"

"You're going to a bar to go online with Zoe. You'll have lots of company. I want some company."

Jack's eyebrows rise, wrinkling his bald forehead.

Diff stares at the disembodied head for a while. It's no accident Jack brought this up now. He knows they are in a hurry to deliver the software. He knows Diff is tired from working ten-hour days. And he knows that Diff's meeting Zoe tonight. Jack knew the best time to bring this up and the probability of Diff's giving in. He'd have run the simulations.

Nothing's more frustrating than arguing with an AI.

"Fine! I'll get you a cat!"

Jack smiles. "Black for Halloween," he says then stops smiling. "Bring it in tomorrow."

Diff opens his hands and grapples the air as though he could crush his frustrations. He says, "Yes," hating that Jack saw the loophole. He'd have put it off for a few weeks. "Can we get back to work?"

Jack stays focused and they finish, test, and deploy the financial application by 9 p.m. It goes quickly, which is how development should happen when working with an AI. A few successes such as this, and management will forget about the extra millions it took to get the AI operational. Consciousness isn't a mathematical certainty. More art than science, Jack's bring-up took many tries.

As Diff leaves, some of the suits in the office look up at the tromping of his heavy, black boots. In the elevator, he stares at his reflection in the chrome walls--a splotch of black with arms and a head, his artificial hand matching his black T-shirt and jeans. He presses the lobby button with his hand made of nano, but instead of moving, the elevator says in a pleasant voice, "Due to new security procedures, please select which floor using your hand or nose."

�Picky," he says and flips it off.

There's a new decal above the button panel that reads Touch ID.

"I want to change floors, not date you."

He presses the button with his other hand.

As the elevator starts its drop, he lifts his elbow and sniffs and decides that if his odor is acceptable to the elevator, Zoe'll be fine.

Diff disembarks from the subway and walks down the sidewalk, passing quiet electric cars stuck in traffic. Up ahead, a crowd is gathering near a group with a megaphone that is doing a lot of cussing and shouting.

Diff pushes into the crowd because the place he's meeting Zoe, Cyber Scuba Barfly, is at the back of the square. A dozen or so people stand near the fountain at the square's center, holding signs that read things such as: Allies don't let Allies war ALONE; Help People's Rep. Of China!; Made in China--Save China; and US in IndoChina war now!

A no-man's land exists between the crowd and the group. In the center of the group, a guy wearing khakis and a thin, black beanie alternates between shouting about the virtues of a war economy and cussing out anyone from the crowd who tries to reason with him.

Diff's heard of these guys, the Protest Warriors. He enters the no-man's land, making for the Cyber Scuba Barfly, not looking at the protestors and wearing his best don't-fuck-with-me look.

The guy with the megaphone shouts, "Hey! Yeah you with the Fu Manchu. Is that a nano-hand? You a vet?"

Diff shakes his head and keeps walking.

"Did you go to Berkeley?"

Diff stops and realizes what a dumb-ass move stopping was.

"Maybe. Who's asking?" Diff says.

Some of the Protest Warriors salute him, maybe sarcastically, maybe not.

The guy lowers the megaphone and says, "I think we had some classes together."

Diff stares at him and notices his Asian eyes, but his cocky posture marks him as American born.

"I'm not a vet. Sorry, I don't remember you," Diff says.

The guy lets the megaphone dangle from its wrist strap and waves him closer.

What the hell can happen? Diff decides and walks up to them. The guy with the megaphone pushes between an angry-looking frat boy with a sign that reads Enough is enough, let's WAR already! and an older, white guy with a furry winter cap that has a red star.

"What?" says Diff.

"It was Intro to Logi' Calc'. You ever use that shit?" He crosses his arms, letting the megaphone hang from around his elbow.

"Yeah. I work with an AI," Diff says.

"Not many get that chance." Both of his eyebrows rise, nearly touching the beanie. "Pure software?"

Diff says, "Yeah. I've got to go. I'm meeting a--"

"Pure soft didn't work for me. I like moving shit around, so I went the nano route."

The guy's mouth hangs open, and his eyes dart left and right for an instant, as if he's both paranoid and thinks Diff's an idiot for not noticing something brilliant.

Then Diff remembers: A panic in the College of Engineering where everyone came down with smallpox. Except they hadn't. It was a cosmetic nano prank. The instigator was expelled and arrested for allowing unregistered nano to self-replicate. A video of the incident was posted on a MyWarz brag site, signed SickDevil66.

"You're SickDevil?" Diff asks, arching his eyebrow. "Didn't you get your ass arrested?"

SickDevil smiles. "Only because I didn't know how to repurpose what was already there. Call it a failure of the Berkeley education system."

"That was some mess. Why are you with these yahoos?"

The guy with the red army hat flips Diff off.

SickDevil sets his hand on the guy's shoulder and says, "Because it makes sense. We have limited resources in the world, and we need a good war to weed out the less desirables so we can live in the lifestyle to which we are accustomed."

He says it in the easy voice of a professor who's explaining something that has been conclusively researched.

"Fuck yeah!" says the frat boy with the enough is enough sign.

"War is a natural and essential part of life," SickDevil says.

Diff points his thumb over his shoulder at the Cyber Scuba Barfly. "Got to--"

"Why are you out here anyhow?"

Diff, not interested in any more discussion, backs away. "My AI wants a cat for Halloween." He says it sarcastically, but the way SickDevil's eyes widen means he didn't catch the tone.

"No shit? So it's getting bored?"

Diff takes another step back, annoyed that this guy can't see that the discussion is over.

"I hear they need a stimulating environment. I bet you're looking for a nano-pet, something you can leave at the office and not worry about it shitting all over the place. Let me help you out!"

"No, no. There's a place just up the street," Diff says, fiddling with his beard.

While Diff rolls part of his beard between the thumb and index finger of his nano-hand, SickDevil stares at his hand.

"They'll overcharge you for a basic model, and then you'll need to pay a monthly or it'll just laze around. The stuff I use is off the shelf but high quality. It'll only take a few minutes to throw together."

A message light tagged with Zoe's icon flickers in Diff's vision. She's wondering where the hell he is. He replies with a templated BRT.

Diff says, "I really need to--"

"Why the nano-hand? It's clear you like black, but most people like their limbs to match."

Diff likes the guy's straightforwardness, so he says, "Too much nerve damage for a bio replacement." SickDevil waits for him to say more. "It's a long story. I've got to--"

"Make it short, then."

"I'm supposed to be staging an assault in Inter-ring," Diff says and starts walking from the circle of protestors. A group of people who had tried to reason with the Protest Warriors are being harangued by them, but SickDevil stays focused on Diff.

"Which ring? Third? Well, watch yourself. There's going to be an action there. Hey, what's your favorite animal?"

Diff doesn't know what the "action" talk is about, so he says, "Ferrets," to really mix it up.

"Ferrets? Think about this. If those bastards multiplied like people, they'd overrun the planet without a natural predator. They'd be like us, top of the food chain."

As if it were behind Diff's skull, a gong rings, shaking his vision. Zoe's not known for having patience.

SickDevil stares into the space between them as though he's taking a call too.

"Shit! Got to go," SickDevil says, handing the megaphone to the red-army guy.

SickDevil breaks from the group of Protest Warriors. As he leaves the square, he pumps his fist in the air and shouts, "Viva la Ferrets!"

Diff's with Zoe on the third ring with the rest of their friends, their avatars wearing skin-tight clothes and sporting throwing stars and broadswords edged with molten plasma--something that Euro-Japanese ninja might use in some far-flung future. They are in a desert that could be in Arizona, huddling together on a tower of red stone, spying on a mecha brigade supported by time-traveling magic-users.

The mechas, battleoids and a hover tank, are circled so they can sweep their sensors in all directions. The mages are in the center, sheltered beneath a shield, performing a ritual sacrifice of a lizard-man they've captured.

Diff suggests they distract the battleoids so the others can hijack the hover tank when Zoe grabs his arm, in the bar and in virtual space, and says in both real and virtual, "Look! Look! Look!"

A shit-ton of ferrets scramble out of a hole in the ground near the mechas. The creatures pour into the encampment like a flood, burying the wizards and their shield and covering the hover tank beneath their bodies. The battleoids stomp their feet and fire into the mass, creating purple pools of writhing bodies.

�Purple blood?� says Diff.

The purple stuff sticks to the battleoids' feet; one by one, they become gummed up and fall to be buried beneath more ferrets.

"How many more can there be?" Zoe asks. The level of ferrets rises foot by foot.

"The ssserver isss overloading," Diff says.

Jon, the elf archer who specializes in killing mages, says, "I'mmm going to give it a gooo and see what happensss."

He leaps from the tower, falling slower and slower as ferrets overrun the entire third ring, his mouth open in a yell that is reproduced in hicks and jerks. Before he lands on the mass of them, the ring shuts down.

"That guy's an asshole," Zoe says after Diff recounts the conversation with SickDevil.

Their extra-res cyber scuba goggles lie next to their drinks; the goggle ring impressed into her face is almost faded. The cos-nano in her hair changes from pink to blue as she gulps the last of her drink, and Diff thinks about the prank that SickDevil pulled off at Berkeley. No telling what he could do now.

Diff says, "Maybe the Protest Warrior shit is just a front for some inadequacies he's hiding. Like maybe he sells Avon."

Zoe smiles. "Let's not get carried away. It's not like he has a Fu Manchu." Diff doesn't smile so he gets punched in the shoulder.

He frowns and says, "A realistic-looking nano-hand saves the surprise up for when people shake it and they realize what it is. A black nano-hand surprises people when they first see it but not when they shake it. Grow a Fu Manchu, and no one's shocked about anything."

Diff leans back, twisting one side of his beard around his nano-hand.

"I thought you had it because it's sexy," Zoe says, and she cups his beard-entwined nano-hand.

"Now that's an apology," Diff says with a big grin, and they both laugh.

Zoe checks her handheld and says, "I need to go. We'll do plenty of drinking tomorrow. What're you dressing up as?"

Diff stares across the room, thinking.

"You still haven't decided?" Zoe asks.

"It's not yet the last responsible moment, so don't oppress me with your rampant planning."

"The party's tomorrow! When is the 'last responsible moment'?"

"Let's meet at the costume shop. I'll pick something out then."

Diff glances across the bar and grabs Zoe's arm. "SickDevil just walked in."

She watches SickDevil, her eyes narrowing until her lashes touch. "I'm leaving now or I'm going to kick his ass. See you tomorrow."

Zoe leaves in a different direction as SickDevil takes her chair.

"Was it something I hadn't said but would've?" he says, smiling. "She's in all black too. What's up with the monochromatic conspiracy?"

Diff shakes his head. "People don't like having their games crashed."

SickDevil pokes at Diff's goggles and smirks. "Extra-high res huh? I bet you could really see those ferrets."

"You'll be banned from the server."

SickDevil rolls his eyes. "I'm glad you got to see that. Ferrets overrunning the world because they can't control their own numbers. With people, we only have other people to kill us. We're still having too many babies, and we're running out of resources. That's why we need to get involved with the Indo-China. It's not bloody enough. Neither side has the balls to drop nukes. Get us involved and we'll turn it into the real deal."

"You realize you sound like a lunatic?" Diff says.

"Yeah. That's what the Church said to Ptolemy--"

"Heretic."

"Splitting hairs. The problem is that we think with our emotions too much and miss what's natural. You work with an AI. Ask it if it sounds like lunacy."

"Jack wouldn't be able to make an assertion without data."

SickDevil smiles. "I knew you'd say that!" He sets a data chip on the table, snapping it down like a trump card. "Have him run this."

Diff makes a face. "I don't load things I get off the street."

"Right, and since you're smart, you'll run this in an isolated region where it can't do anything to you."

Diff just looks at him.

"Shit, it's no more dangerous than the Game of Life. It simulates parallel universes filled with worlds and civilizations. Run it at high speed and watch the results. Those that survive are badass mother fuckers."

Diff doesn't take the chip.

"I'm telling you, it's all about war. We need war to cut down on all the dumb asses out there. It's part of Darwin's natural selection," SickDevil says.

"I don't need a simulation to know war isn't natural."

"It's everywhere! It's a necessary activity for survival. Look at ants! Those little fuckers are always fighting with their neighbors because they know the colony with the best access to food is going to survive and grow bigger than the other guy."

Diff says, "Just because ants don't cooperate with other ants doesn't mean we need perpetual war."

"You're thinking with the emotions that society programmed into you. They made you share in kindergarten; that wasn't natural! That's why I want you to ask your AI about this. For years I've been working my ass off to step 'out of the box' and it's hard. People get pissed off when you do things like I did at Berkeley or what I just did on the third ring. But I have to do shit like that to understand myself and what society has done to me. Jack--that's your AI's name? Isn't it crazy shit that they choose their own name when switched on?"

Diff sips his beer and watches SickDevil, fascinated with what he's seeing. Either SickDevil has a point or he's completely crazy . . . or the guy needs to be punched in the mouth for wasting everyone's time.

SickDevil bangs his finger right next to the chip. "So Jack doesn't carry that baggage. He'll tell it like it is because he's a software model of what we'll become--the next step of our evolution! They don't have the political or emotional biases that screw us up. It's going to take a while for us to straighten ourselves out."

Diff pokes at the chip. "Why do you give a shit what I think?"

SickDevil gets a brightness to his face, as if he's become the focus of a spotlight. He shoves the goggles out of the way, like anything between the two of them would impede what he's about to say.

"Honestly, I wouldn't give a hat full of shit for what you think. But you have access to something that I don't. I want to know what Jack thinks. Have him run that simulation, and then ask him if society needs systems for killing its own population rather than turning the entire fucking planet into one big Easter Island."

SickDevil leans over the table, resting his elbows on network cables, holding his head up with his hands, as if all the talking has pushed him to exhaustion.

Diff sips his pint and tries to form a summary of all the crazy he's heard tonight.

SickDevil points at Diff's hand and says, "So what's its story? Nerve damage, et cetera?"

"Stupid childhood stuff," Diff says.

"Come on!" says SickDevil.

"Happened after school. A cousin wanted to show me what happens when a spool of wire is tossed across high voltage lines. It jumped around like a fire hose, and he'd have taken it in the teeth but I grabbed it. I was resuscitated in the hospital with a hole burned in my foot, which made the best ground, and a nano-hand."

"Damn!"

SickDevil finally shuts his mouth. His head droops and his eyes shut.

Diff gulps his beer, feeling some satisfaction that all the crazy has worked the guy to burnout.

SickDevil's eyes open. "It's aggravating the piss out of me that you lost your hand instead of letting your cousin collect his Darwin Award. Jack would've let that fucker electrocute because in a world with surplus life, you don't waste resources on those that aren't contributing to survival."

Diff shrugs. "I was stupid for going along with it, but I was twelve at the time," he says and finishes his beer. "I'd better move on. I don't want to be too Neanderthalic in front of Jack."

"Almost forgot," SickDevil says and pulls a finger-length tube out of a pocket. "His cat."

SickDevil unscrews the lid and tips onto the table a pile of dust that shimmers and shapes into a full-sized, black cat.

Diff stares into its yellow eyes, bright irises with flecks of dark, pupils reflecting Diff's face. It mews.

Diff says, "You do good work."

To Jack's delight, Diff gives the cat run of the office, and Diff finds that having it makes working with Jack easier. Whenever Jack becomes difficult, Diff bribes him by petting the cat until it purrs, letting it play with his shoelaces, or "painting" targets with a laser pointer for it to attack.

"The cat is good company," Jack says.

"You're welcome," Diff says.

The cat licks Diff's nano-hand, enjoying its attention better than a real cat, or person, would.

He has to leave for the costume store soon. Diff starts a safe terminal and loads the code from SickDevil's chip.

The code's professionally designed, so SickDevil is at least as competent a code designer as a nano developer. The simulation generates as many civilizations as resources allow. The seed civilizations are diverse: historical, mythological, oceanic, randomly generated, and fractal. He allows it to execute a few trillion iterations then examines some of the survivors. One looks like something out of Tolkien.

"Jack, what do you think of the U.S. getting involved in Indo-China?"

"Based on historical data, loss of life would be significant and the consumption of resources would be high."

"Would there be a net gain in available resources for the survivors? Or would it be more beneficial to invest resources consumed by war into energy discovery and developments to make society more efficient?"

"I don't have enough data to make a conclusion," Jack says.

Diff says, "I've loaded a simulation into an isolated domain. Allow it to execute on idle resources. Evaluate it from time to time and contact me when you notice characteristics common to the survivors, such as foreign policies, military strength, innovation, et cetera."

Diff looks at his handset. "I'll see you tomorrow. Contact me if you have any considerations as the simulation runs."

Diff scratches the cat's head.

"Don't let the cat run amok while I'm gone."

Outside the costume store, Diff watches the projected animation on the store window for inspiration. Ninja drop from the ceiling to fight a snowman wearing enough makeup and leather to have gone goth. Though the ninja's monochrome--black only--jammies and head sock are tempting, he decides to pass because monochrome is his lifestyle, and Halloween is about exploring something different.

An audio-link request flashes in his vision. The request is tagged with a devil's head, its mouth open as if it were going to hurl, and its face turning a greenish tinge. Diff's mildly amused so he accepts the link, and right away, SickDevil talks a hundred miles an hour.

"Am I right or am I right?" A keyboard clatters in the background. "Your AI totally says I'm right! Go on! Admit it, fucker!"

"The simulation hasn't run enough iterations."

"The hell! I thought you had some hardware! We're talking real AI, aren't we? Not one of those fuzzy heuristics engines that Redmond keeps pushing. Those things are shit!"

Diff wants to tell him to fuck off but decides things might go more pleasantly with restraint; he must be getting old. He says, "Jack says thanks for the cat."

The keyboard sounds stop.

"The cat did what? Oh. Yeah. Tell him he's welcome."

The keyboard sounds start again.

SickDevil says, "I went through the work to build a simulation and a cat, and you didn't start the simulation first thing?"

The guy actually sounds hurt.

"Hey, I started it as soon as I could. It's running right now--"

"Probably in 'nice.'"

"I can't impact business ops. The administrators would ask questions."

"I see." The keyboard sounds are fast and furious. "We'll do this the hard way."

"Hey, I'll let you know what Jack thinks as soon as he's made up his mind."

"Yeah," SickDevil says, sounding disinterested.

The connection abruptly closes, and Diff realizes he's still staring at the window, at the bloody mess the snowman made of the ninja, and he wonders from what plane of existence SickDevil comes from. Sure the cat was nice, but hey, SickDevil never said anything about a deadline. Prick.

A message light flashes in his vision. It's a message in text from Jack that says he's added every idle computing resource the company has and the simulation is still requesting more and that the containment environment is adding at least 25 percent of overhead.

Diff shakes his head and sends Jack a voice message: "Keep containment in place. If the simulation can't operate with our unused resources, then I'm not interested."

If there aren't results in the morning, he'll shut the simulation down and give SickDevil's reputation a major ass-kicking for "not contributing to society."

Diff's hand twinges and his wrist hurts as if it's being squeezed in a vice. He gasps and cradles his hand, wiggling the black fingers until they relax. The twinge has never happened before, though the doctor warned him of ghost pains.

Massaging his wrist, he enters the store. The place is mobbed with people turning into zombies, Egyptian gods, knights, cyborgs, and superheroes. He pushes through the bedlam until a green-skinned witch blocks him and bats her inch-long lashes, smiles, and holds up a bejeweled sacrificial dagger with a foot-long blade.

"Nice," he says. He's still staring at the hilt and the jewels covering its body when she quickly thrusts it into his chest. Stunned, he watches blood leak down his shirt then looks at the witch, too shocked to feel pain.

"You should see your face right now," says the witch, and she yanks the dagger away.

The blood running down his shirt shimmers as tiny particles change color to dagger-gray, remaking themselves into a blade.

"You didn�t recognize me," she says with a cackle that ends in a giggle.

He is having trouble getting past the green skin, the dime-sized warts on her three-inch nose, and her oval cat eyes, but her giggle gives her away.

"I�m surprised, Zoe. I would have guessed you more of the dark elf type."

The witch smiles and the nano in her eyes change into grinning skulls.

"You know what you want to be? We have to hurry. Jon'll be mad if we're late."

Diff wiggles the fingers of his nano-hand and wonders if he should get it looked at.

"I don't know, Zoe--"

"You have to go!" She leads Diff by his arm to a shelf of bottled costumes and takes one with a Centurion on its label. "Try this on."

Diff takes the bottle because he knows he's had it. He opens it and dumps its contents onto his head.

Zoe holds up a mirror as the contents, a lump of what looks like ash, diffuse into squads of dust motes that receive orders from the manufacturer's computer and swarm to their tasks. In seconds a moving front of dust solidifies around his head into a Roman helmet, and another sortie propels above the helm, forming a flowing, red pennant attached to the top.

His chest is obscured beneath a haze of particles that shift over his T-shirt and settle into a shiny breastplate.

The light touch of nano presses against his arms, squeezing then loosening into a stretchy material forming brawny biceps. Skin-colored nano presses his jeans against his legs, creating faux muscles.

"Nice legs," Zoe says.

She hefts Diff's sword from its sheath, a traditional Roman gladius.

"Your weapon is so much more manly than my little dagger."

Diff smirks. "Jack also uses flattery to get what he wants."

Zoe hands back the gladius. "I didn�t know AI stooped to human traits."

"Whenever he sees an advantage to it," Diff says, sheathing the sword. To test its heft, he violently draws it, but the hilt separates from the blade.

"It's broken!" says Zoe. She fires a message at the attendant.

The attendant, a woman loaded down with cos-nano who looks like she's in her twenties but moves slowly and takes each step carefully, arrives and insists on reading through the costume's feature list, trying to find mention that the broken sword is supposed to be a feature.

Failing that, she looks at Diff and says, "That costume really suits you."

"No reasonable person expects to buy a costume with a gladius that breaks," Diff says.

The woman puts her hands on hips, "Nano doesn�t break."

Diff makes a fist with his nano-hand and bangs it against his chest armor, nano on nano, and nothing happens outside of the rap of his hand on metal. The woman has a point. Each piece of nano is the same as every other piece, a completely redundant system. If one part in a million or even a thousand breaks, extra nano slides over and replaces it, and the damaged piece is sloughed off like a dead skin cell. It's in the programming.

Zoe says, "Regardless, something is wrong with it."

"It would require a systemic failure," Diff says.

The woman is moving on to another customer when Diff's belt crumbles and his scabbard falls with it to the floor, all of it turning into a pile of dust.

The attendant turns around. "I'll send that back to the manufacturer," she says. She holds the bottle above the dust pile, which prompts the nano to flow back into the bottle.

Diff's vision goes black as a jolt of pain travels from his hand up to his elbow. He sucks in his breath at the shock.

"What's wrong," Zoe asks.

"My hand! It really hurts today."

Zoe rolls her eyes. "You're going to this party. Here's another Centurion. Try it on, big boy."

Diff sighs and pours the nano over his head, thinking that maybe he really is getting old. After the costume works flawlessly, the two of them leave for Jon's, Diff rubbing his wrist and hoping there isn't another flare-up.

When Diff and Zoe reach Jon's party, it's rocking with fog, laser lights, and people dancing and drinking punch. Jon's second-floor apartment, a studio built inside what used to be a warehouse, has large windows overlooking a nearby industrial district and a double-wide steel door.

Diff and Zoe watch for Jon, but so far they meet a troupe of goth cheerleaders, a furry in the form of a six-foot-tall lolcat, and a pirate and ninja who can't get along.

Fog rises from the punch bowl, next to which are cookies defended by four-inch-tall nano-brownies, which wave their tiny fists in the air and shout insults.

Zoe picks one up. The brownie struggles between her fingers as if it's afraid of her long, black nails.

"Jon must have spent a fortune on this," Zoe says.

A flying faerie blows kisses at Diff. He plucks her from the air and notices one of her slippers is missing. He examines Zoe's captive and he says, "There's a strange bend in his knee."

Zoe says, "Jon must have gotten blemished merchandise."

"Never heard of blemed nano," Diff says and releases the faerie.

The faerie flies to the lolcat and declares its love. The lolcat shakes its head and points at a sign hanging from its neck that reads, I can haz Zazzafraz. Next to the cat is a goth Lolita cheerleader: her pigtails bouncing as she dances, her name--Zazzafraz--on the back of her sweater top, her sleeves hanging past her fingers. She pouts at the faerie then flicks it away.

"Ooh look," Zoe says, watching something in the punch.

The dorsal fins of sharks circle the lump of dry ice. One shark floats belly up.

"Poor little guy stopped working," Zoe says and pokes it with the ladle. It doesn't move so she fishes it out and leaves it on the table.

Diff accidentally scoops up a shark. He decides it would be cool to have it in his drink, so he pours it into his cup. But when he moves away from the table, it leaps from his drink back into the punch bowl.

"Very cool programming!" Diff says.

He and Zoe are searching for a place to sit when his nano-hand starts twitching. He switches the cup to his other hand and sits with Zoe, thinking he needs to take a vacation.

Diff and Zoe are in a deep discussion about third-ring combat strategies when Jon, fashionably late to his own party, enters his apartment.

"Hoi, centurion. Or rather, Hoi, unusurion, since you've left your squad at home."

Jon is the spitting image of his virtual character, an elf with a green cloak, mid-calf boots, and a long sword. "Salve amicus," says Diff, a Roman greeting. "Nice party for an elf."

Zoe asks, "Where did you get all the nano-toys?"

"A friend at NanoWare hooked me up with some prime stuff."

"One of the sharks isn't working," Zoe says.

Jon's eyebrows drop low over his angular, elfin cheekbones. The cosmetics on his face aren't good enough to be nano. Typical Jon, showing off by going the high-maintenance route.

Jon says, "It's supposed to be flash stuff."

"It's been a bad day for nano," Diff says and walks back to the bowl for a refill but stops.

The brownies are standing in rank and file, and the faeries hover above them as if the two groups are planning something.

"Something wrong?" says Jon, brushing past Diff. As he grabs the ladle, the four-inch-tall brownie host marches to the bowl. He's dipping the ladle into the bowl when faeries dive past his shoulder and skim over the punch.

"The devil!" Jon says, stepping back.

The faeries make a second pass, and shark fins emerge and shadow beneath them. Then the sharks launch into the air, some catching faeries in their mouths and taking their victims back into the punch. A tiny, feminine arm floats to the surface of the punch.

The brownies climb the side of the bowl and toss spears at the shapes beneath the surface. A skewered shark floats to the top. Two brownies stand on the edge of the bowl and lean over, their fellows keeping them from falling in by gripping their belts. The two pull out the skewered shark and toss it to the table. Other faeries and brownies hack the shark to pieces with small knives.

Diff says, "They're supposed to do that?"

"I think they�re buggered," Jon says.

Diff's message light blips on, blinking an urgent red icon. It's from Jack.

A shark jumps out of the bowl, hurling itself at Zoe with its mouth open. Diff snatches it out of the air. The nano-fish wriggles in his grip, its mouth with rows of serrated teeth opening and snapping shut. Diff holds it tightly, not wanting to lose a finger, not even a nano one.

"Let me see that," says Jon.

As Diff holds it up, his hand spasms and crushes it.

"Sorry," he says and tips the remains into Jon's hand.

Someone pounds on Jon's door loud enough to disturb everyone despite the cranked-up music.

Jon looks up, his lips pushed out in an angry expression. "Sounds like they're using a battering ram." He shouts, "Use the bloody knob!"

The pounding stops but the door doesn't open. Jon starts across the room but becomes distracted by the attentions of two goth cheerleaders in leather halter tops and chain-link stockings.

A formation of faeries dives past Diff and skims above the battle in the punch bowl. Sharks jump for the faeries, a few becoming victims of brownie spears, others catching faeries in their teeth.

The faeries take heavy losses and change tactics to fluttering above the bowl, scolding and taunting the sharks to the surface, where brownie spears can be effective.

Zoe says, "I've never seen such aggressive toys."

The message from Jack still blinks. Diff moves away from the bowl to read it: I need to talk to you.

The pounding at the door starts again. Jon tries to pull away from the goth cheerleaders but fails, each of them holding an arm.

Diff makes an audio connection to work. "Jack, what�s going on?"

"Diff, I require you at . . ." The stream slows then starts again. "Work."

"What's happening?"

"Too much data. . . packetsss and bitsss. . . a storm. Everything is ssslowing. The simulation has linked to the networkssss."

"How? It's running in isolation? Jack? Jack?"

While the audio connection stalls, Diff thinks about the simulation's programming modules, wondering how he could have missed something. The network recovers the connection.

Jack says, "Cat. . . connected. . . isolation down. . . I said bad cat! Networksss bogging down. Losing too many sss'ycles."

The connection drops. Diff stares at the floor, trying to shut out the music, the flashing lights, and the lasers flickering through fog. He focuses on what Jack said: isolation down, storm, bad cat. It's nonsense.

He's got to go to the office.

"Zoe, I need to--"

"Diff!" She shoves him and a faerie zooms past his nose, cursing at the top of her tiny lungs. Shark carcasses lie all around the punch bowl. The brownies are howling at each other, their eyes gleaming, shaking their spears and knives at Diff and Zoe. The group moves to the table's edge, and one springs through the air and lands a few feet from the table. Diff backs up a step as more of them follow.

A gargantuan knock shakes the door. Jon kisses each cheerleader on the cheek then rushes to the door.

Diff looks down at the gathering brownies and again thinks about the storm, and warlike toys, and the simulation and starts to get the feeling that whoever is knocking might not be someone they want at the party. He turns away from the brownies and shouts, "Jon! Wait!"

Diff catches sight of a brownie rushing him, but Zoe swats him with her broom, sending him spinning across the room. He lands beneath the heel of the lolcat and is crushed.

Jon glances back, looking ready to punch whoever is behind the door. He yanks the door open.

Two red LEDs hover above head level from the dark, and something large steps into the doorway. Jon trips backward as the monster enters, one leg dragging, the other stepping forward on a trunk of a leg. It looks like a cyborg made of leftover parts and a football player. Its head, small in proportion, almost brushes the top of the doorway.

While its red eyes move through the room as if it were a robotic barcode scanner, Jon says, "You. . . Who are you?"

It doesn't answer so Jon says louder, "Just because you are nanoed to the eyeballs to look like a brute doesn�t mean you should punish my door like one."

It still pays him no attention, so Jon steps in front of it and shouts, "For God's sakes! I enjoy a great entrance as much as the next fellow, but grow up a bit."

It brushes past, no hands or arms visible, only a dark metallic, barrel chest and thick legs bending forward as it walks. It moves in staggers, as if drunk.

"Diff!" Zoe yells and swings her broom past his nose. A squadron of faeries dodges over, under, and around the broom. His ear stings where a faerie clipped it, and when he touches it, his finger has blood on it.

Feeling pissed off, Diff chases the brownies, but they surround him and jeer at him.

Zoe comes at them with her broom, but it shakes from her hands, falling handle first to the floor and sprouting feet. Before she can grab it, it rushes across the room, and the guests laugh and cheer as if it were part of an act.

Three brownies charge Diff. He focuses on them, holding his sword, picturing the killing arc that will catch them all. He steps forward and swings one handed, realizing as he does so that he's being an idiot since the sword is programmed like Zoe's dagger not to puncture anything. He doesn't even come close. The sword swings free from his hand, spinning across the room until it crashes next to the entertainment center.

"Your hand's gone!" says Zoe, as the brownies attack, stabbing at his legs with their spears, but Diff's centurion greaves protect his shins.

He jumps and lands on one, crushing it. Another attacks from his back, stabbing its spear into his calf.

Diff yelps at the feel of it, burning like a rough splinter shoved through his skin then twisted.

He kicks back, breaking the brownie at the waist. Faeries with knives dive at his face. He ducks but they collect on his back and stab him, puncturing his back like tacks. Zoe sweeps them off with her arm then catches them in her cape.

He shouts to Zoe, "You take care of Tinkerbell's clan; I'll handle the brownies."

The brownies surround him. One charges and Diff kicks, missing. He spins around, again and again, trying to keep his armored front toward his attackers, but feels outmatched.

A brownie toward the rear of Diff's attackers tosses a spear at a goth cheerleader. The spear strikes her in the thigh, between the links of her hose. She yells and points at the brownie. Then the entire cheerleading squad attacks, stomping brownies beneath their military-style boots, wiping out the attackers on Diff's flank.

The brownies are quickly crushed, and when Zoe nets the last group of the faeries in her cloak and dashes them against the wall, the guests cheer. Jon smiles and pats the large guest on the back, pointing at Zoe in a probable introduction.

Diff is saluting Zoe when she shouts at him, "Look out."

The broom, which has been ricocheting off the furniture and walls, just misses Jon and charges Diff, its bristles madly poking at the air. Diff reaches to catch it, one of his hands looking wrong.

The broom bounces off his armored chest then goes at him again, laying into him with its bristly head, scratching at his chest as if he were an offensive source of dirt.

Diff freezes, having not fully understood his nano-hand is gone, and stares at something he has never seen: the skin the doctors had stretched over the bone that once connected to his wrist is smooth and pink like the flesh of a cheek. He's always imagined beneath the nano there would be the end of a jagged bone, blackened skin, and the smell of melted hair. Never this.

Zoe knocks the broom down and stomps its handle until it busts in two.

The crowd claps. Someone turns up the music, and the goth cheerleaders form a line and do a techno-stomp dance that shakes dust from the ceiling.

Zoe sets her hand on Diff's shoulder while he stares at the stump.

"What's happening?" Zoe says.

Diff remembers the painful twinge from his hand today. It had never done that before. "It's the nano."

"Nano?"

While Jon talks to the new guest, trying to find out who it is, the ninja strikes the pirate with neon nunchakus, which bounce harmlessly against his shoulder. Before the pirate can retaliate, the ninja hides behind the large guest.

Diff says to Zoe, "I'm worried. Jack's having trouble with a simulation, and it's causing a bit storm, meaning it's sending so much data that it's using up all the bandwidth. The simulation might be screwing up the nano."

Zoe glances at the drawn-and-quartered shark. "They're not screwed up. They're warlike."

Diff watches her pupils change from jack-o-lanterns to crucifixes and says, "It's got to be SickDevil! He was kicked out of Berkeley for shit like this."

Zoe's eyes start to water. She pulls at one eyelid then the other. "Something's in my eyes."

Both eyes open for a moment as she realizes what's happening at the same time as he does--her costume contacts are nano.

"Get them out!" Diff says. The dark crucifixes that covered her pupils are now broken shards.

While she works the lenses out, Diff notices her green hands and realizes that their bodies are covered with nano.

Shouts of surprise carry above the music. The ninja's throwing star strikes the pirate above the eye patch. The pirate collapses, the star embedded in his forehead. The lolcat falls, its tail wrapped around its body and squeezing it like a boa constrictor. A goth cheerleader drops to the floor to remove her chain-link hose. She starts yanking it, trying to tear it off, swinging her whole body into it, but her legs continue turning dark and losing circulation.

Diff slips his costume's bottle out of his pocket and holds it over his head, waiting for the mini dust storm, but nothing happens.

"Get rid of all your nano," he shouts and works to unbuckle his armor and tear off his costume legs. It's difficult with only one hand.

While his hand is busy, he tries an audio connection to SickDevil. After his armor's off, he lets the connection request continue and starts another to Jack. Jack answers as Diff frees himself of the last of his costume.

"Difffffff you haven't llleft yyyyyet? The financialll jobsss . . . affected."

Diff notices Zoe helping Zazzafraz free the lolcat. The cat's tail has torn itself free and is tightening around the cat's chest.

Diff says, "Jack, forget the office. The bit storm is screwing up nano. Kill the simulation!"

Diff listens for status, one ear plugged with a finger and doing his best to cover the other with his stump, listening for Jack to say that everything is back in control. Jon collects ruined costumes from the floor and throws them out the door: bits of fabric that wiggle and wave; chain-link stockings that catch at his hands; broken swords, guns, and brooms that develop vendettas against anything they touch.

Diff's wondering if he's lost the audio connection when the large guest staggers and bumps into a wall, seemingly unconcerned.

"Is that guy in trouble?" Diff shouts.

The unknown guest stumbles into the entertainment center, and something small darts from underneath the equipment to hide under the nearest table. A rat, Diff decides. Not surprising for this neighborhood.

"--can't kill--," Jack says.

"What?" Diff says.

"Ssssimulation has plugged up command queues."

"How did it break isolation? I'm telling you, the damn thing didn't have a line of network code!"

"--sss cat," Jack says.

"What?" Diff says.

"I told it to stopppp . . . bad kitty . . . iiinterfaced into terminal . . . injected new code."

"When?" Diff says, feeling a cold fury toward SickDevil.

"Eighteen forty-two."

Diff remembers outside the costume shop, how the keyboard was clicking while SickDevil talked and how distracted he sounded. Diff thought of how disappointed SickDevil was that Jack didn't yet have an opinion because the simulation was started so late--as if Diff and Jack weren't making the grade.

SickDevil, Diff realizes, was sending orders to the cat; SickDevil used the cat to jailbreak the simulation.

"What else did the cat do?"

"It lay on your keyboard and purred."

Diff looks across the room in the imagined direction of SickDevil and stares murder. Zoe and Zazzafraz are giving the lolcat CPR. Two goth cheerleaders have the tail stretched between them and are tossing it out the door.

The pirate's hat lies on his face, covering the sight of his eyes frozen in their upward stare at the throwing star.

Diff says, "Get the cat's terminal ID and reprogram--"

"--did and I shut it down," says Jack.

The rat he saw earlier darts from beneath a table and slams into a chair, knocking itself over. For a moment, its black legs wriggle in the air before it flips itself over and runs right at Zoe, who's giving mouth-to-mouth.

Her reaction is sudden: her back snaps laser straight, and she jumps up and hops around on one foot, kicking out with the other. Diff runs to her as she slams her foot onto a tabletop and tries to dislodge the animal by scraping her leg across the table. While her leg is stretched out, Diff recognizes what's climbing her ankle--his state-of-the-art prosthesis.

"Get it off me!" she shrieks, swinging her foot off the table and going back to hopping around.

A goth cheerleader starts to push Diff aside, but he stops her. "No! I've got it!" he says, glancing at her heavy boots.

Like a spider, the hand scales her leg to her knee, just below her skirt.

"Hold still," he says.

"Get your fucking hand off me!" she shrieks as the nano-fingers pass her knee and wriggle beneath her dress's hem.

Diff grabs it and pulls, but the hand clenches her thigh and Zoe screams. Inside of the hand's cuff, he sees a terminal ID.

"Jack!" he shouts. "Reprogram my hand," and he rattles off the ID.

"Get out of the way!" the goth cheerleader says, her boot off and ready to smash his nano-hand.

Diff fends her off with his stump until the hand goes limp and he can remove it from Zoe. Filled with adrenaline and feeling responsible for the disaster, he yells at Zoe and the goth cheerleader, "What the hell were you thinking? This is damn expensive."

He slips the wrist coupling over his stump. It reactivates, clamping onto his wrist, and Diff wriggles his fingers.

"See? All better."

"Is it going to stay that way?" Zoe says.

Diff just stares at her. He doesn't know.

Zazzafraz stops giving the lolcat CPR and says, "Something's wrong. He's not ventilating right."

She peels the nano-suit away from the man's chest but stops because it tears his skin.

"The suit's grown into him," she says.

The color of the man's face is as gray as his furry body, looking very dead. The goth Lolita cheerleader kneels and holds her date's head across her knees, her pigtails sticking to her tear-streaked cheeks.

Everyone silently watches until Jon says, "I can't get a connection to emergency." He turns away and scoops up the last of the abandoned costumes and throws them outside. He stays just outside the door, leaning over the railing.

Diff receives a data message with the devil icon: Has Jack told you what you know to be right but won't let yourself believe? SDev.

Diff sends back: People are dying, asshole.

A response comes back: If you were to do it all over again, would you have grabbed that wire?

Jon swears, rushes back inside, and bolts the door.

"There's something moving around out there, and it isn't trick-or-treaters."

The music stops with the sound of Jon's entertainment center crashing onto the floor. The guest in the nano-suit stumbles over the equipment, crushing the electronics. Jon confronts it, the smoking mess of electronics between them.

"I don�t know who the hell you are, but take that bloody costume off before I shove you out the door and feed you to whatever it is that's out there."

A limb whips from its metal body, thin and flexible as a car's antenna but tapered to a point. Jon steps back as it swishes in front of him then retracts back into the body.

"The devil!" Jon says, looking down at his leather jerkin, the pink of his skin showing through a slice running from his belt to his chest.

"This isn�t nano. It's real leather, you bollix."

No one in the room moves, waiting for a response. The guest staggers backward onto the coffee table and crushes it with one trunklike leg.

"So that's the way of it," Jon says then turns to face Diff, rolling up his sleeves. "Give me a hand with this wanker."

While Jon's back is turned, the guest charges. He accelerates forward, legs striding out in an odd and jointless way. More limbs sprout from its body, wavering like snakes trying to break free. Jon spins as the guest slams into him, the limbs coiling around him, squeezing Jon to its chest as it crosses the room and crashes into a wall. One of Jon's arms hangs free, pressing against the wall, trying to get him free.

"Jon!" Zoe screams.

Everyone rushes to free Jon, but more limbs whip out from the thing's metallic back. Diff retreats with a slash across his arm. Zazzafraz falls to the floor and has to be dragged to a safe distance. She bleeds from a slice that has splayed her thigh.

"It's a bot made of nano," Diff says. "A giant chunk of nano."

While putting pressure on his cut, he decides that they need another approach, something powerful to reprogram it.

The bot's legs keep working, pushing Jon further into busted-up wallboard. Jon's arm shakes with his effort, fighting to push free.

"We have to help him," Zoe says and moves closer, but a limb whips past her face.

Diff sends Jack a message in text: Jack, it's an emergency. There's a mass of nano inside of Jon's apartment. It needs to be deactivated.

Jack responds: I need all the IDs. Querying them is too slow during the storm.

Jon's hand starts shaking, his palm lifting from the wall. Then it goes limp.

For a moment Diff panics that it's all over for Jon. But some habit formed during all the late-night gaming kicks in, and he focuses and sends: Impossible to get all the IDs. You have to try without them. Jon's being crushed.

Jack responds: Simulations show that Jon will terminate within the minute. You may have success by breaking the nano up.

Diff watches more limbs whip back at them and wonders if something has wrecked Jack's logic engine: Huh?

Jack: I've got your hand's ID. Reconfiguring.

The nano in his hand scuttles and slides, thinning and elongating until it is a four-foot machete blade.

Jack: Optimized for slicing.

He's lost the little tactile feeling he had of his fingers. Now there's only the feeling of a palm. The blade from edge on is nearly invisible, seemingly thin enough to part molecules.

He moves close to the bot and swings his hand-turned-machete, chopping through two limbs in one swing.

Limbs swing at Diff from all directions at the same time. Diff whips his hand in a windmill-chop, and limbs drop to the ground. More limbs sprout from the back of the bot.

"Take out its legs!" Zoe shouts.

A limb whips at Diff's head. He dives to the floor and swings for the bot's legs but falls short. Above, a forest of limbs sprouts, its shadows weaving across the floor.

He lunges closer and cuts deep into the legs, hoping he doesn't amputate Jon's. The bot tips off its legs and crashes onto the floor beside Diff. It lies on its back, and rather than push itself upright, it reshapes what's on the floor into legs. Diff stands as a new head with LED eyes emerges from what was its chest. The head swivels to stare at Diff as he swings and lops it off.

Diff circles the mass of nano, swinging furiously. Each strike, a blow to SickDevil and his asinine outlook on life. Each chop, an attack on SickDevil, who thrives on grief. SickDevil is what he'll say to his management, who'll want his job. SickDevil is the name he'll sing to the authorities who will be arresting him in the morning. SickDevil is the name he'll give to the victims' families.

"Jon's breathing!" Zoe says.

Diff glances at Jon, who looks like a fallen hero in a fantasy movie: blood leaking from his mouth, white detritus from the wallboard powdering his jerkin.

"The monster's rebuilding. We need to leave," says Zazzafraz.

"We can't leave Jon," Zoe says.

Driven by SickDevil's simulation, the monster shudders on the floor as parts of its body reassemble or retrain into something new.

There is a scratching at the door that becomes a pounding in the time a goth cheerleader crosses the room to look through the eyehole. She says, her voice shaking, "Another one is outside."

Diff looks at his nano-hand-now-machete, and realizes that he's finally got it. He, the party, Jack, and the software--they are all part of the simulation.

The monster rebuilds but differently. The limbs reattach, but their ends bud and sprout cutting blades, pincers, and hooks. Its body surface has a translucent coating that makes Diff suspicious.

He swings at it with his machete, but the blade bounces off the coating. Legs form beneath the monster inch by inch as it jacks itself higher.

"It's going to attack us soon," Diff says.

Zazzafraz says to her cheerleaders, "Watch the door. Maybe whatever's outside'll leave."

Diff opens a voice channel to Jack. It'll take longer than text, but it's the only way he can ask Jack to do this, to use the only means left to end the simulation.

Diff helps Zoe drag Jon to the far side of the couch. The channel isn't open. The ninja tips the couch so Jon's protected in the nook between the seat and the back. The channel's connection is yet to be made. The goth cheerleaders group by the door, each taking a look and sending messages by text for help.

The monster goes for the cheerleaders. Diff yells at it and pokes it with his hand-machete. A limb whips around and drives a spinning blade into his machete, screeching and sparking against Diff's hand until he backs away, chunks missing from the machete's edge.

The voice channel finally connects as Diff leads the monster away from the goth cheerleaders.

"Jack, the nano is going to kill everyone."

"The simulation needs to be sshut down," Jack says. His voice sounds odd, and Diff wonders if Jack knows what he's being asked to do. Diff throws a punch bowl at the monster then shoves a table into its path. Zoe stays behind the couch with Jon. The ninja ducks into a closet.

"I know," is all Diff can think to say.

Nothing comes over the channel. The monster crashes through the table. A limb shoots forward and punctures Diff's shoulder and starts to pull Diff toward the monster. He jerks away. Barbs hook his shoulder muscle, and he can't tear free. Zoe runs past the monster, dodging a limb with pincers as big as her head, wraps her arms around Diff's waist, and pulls. The barbs hook deeper into muscle, and the pain spreads through Diff's body. The tissues tear and Diff falls onto Zoe.

Diff presses his good hand over the hole, his eyes watering at the pain, his mouth set shut. Maybe Jack has made up his mind and isn't going to respond. Maybe SickDevil is right. Maybe . . .

"Jack," Diff gasps.

"Thanks for the Halloween cat," Jack says.

The pounding at the door stops.

Zoe shouts, "Watch out!"

The monster finishes a step toward them, tips forward, and slams to the floor short of their feet.

"Jack?" Diff says into the dead connection and wonders if SickDevil knows that the simulation is over. Would he care? Or was it just another griefer attack like the ferrets--SickDevil just getting outside of the box.

He remembers SickDevil's speech about humans at the top of the food chain and AIs as the next evolutionary step.

Diff takes Zoe's hand up and stands. She goes to check on Jon. The goth cheerleaders have the door open and are venturing into the dark.

Diff remembers how his cousin seemed to stand still in time while the overloaded line flew through the air, so filled with energy, it glowed like a blue beam. He batted it away. He just reacted. If he'd had time to think, time to run simulations like Jack, would he have risked his life for his elder cousin?

Diff whispers into the dead audio connection as if, somehow, the electrons that once made up Jack will understand:

"I'll give SickDevil your results. I'll tell him he's wrong."

No idea, Diff decides: There's no way to tell if he'd grab that line knowing he'd be trading his life for his cousin's. But Jack did. Jack shut himself off, killing his unique self, to save everyone at the party.

As Diff opens a connection to the FBI, he wonders who the new AI will be when it's brought up again: How will it sound when it talks? Will it like cats? What will it choose for a name?

Nanotech

Weather Underground

Beloved

Vacation Station

Space Suit

The Doctors

Rock, Paper, Scissors, Glass

Between Blood and Bone

Loopholes in Light

Rearranging Ways to Listen

Precognition

Forget It

Englebert

The Alchemist's Wife

Biomagnification

Dust

Swarm, the Queen Commanded

The Next Generation

Sabi, Wabi, Aware, Yugen

The Subatomic Fiber-Optic Deconstruction/Construction Transportation Chamber

MiracleMech

Susumu Must Fold

Nathan and the Amazing TechnoPocket NerdCoat

Let's All Sing Like the Birdies Sing

The Bittersweet Here and After

Mortal Coil

Nanomite

The Professor's Boy

A Puddle of Dead

Everlasting

True Hollywood Story

The Ambiguity Clock

The Rules of the Regeneration Manual

Bit Storm