"Suppose you were a brain in a vat," Hillary began.

"What?" Darren cut in sharply.

Stuart listened with half an ear to the dialogue firing across his chest. Since the three friends all lived on the same block, they walked to school together frequently. It was late February, and the neighborhood was dressed in white from a light dusting of snow two days before. He focused on the rubbery crunching sound under his feet and smiled to himself.

"Suppose you were a brain in a vat," Hillary repeated, speaking each word deliberately. "As in, you have no body. You're just a brain swimming in a glass jar, with a bunch of cords attached to your various lobes, and some scientist is feeding you sensory input through the… what do you call it?"

"Electrodes," Stuart supplied. The wind picked up, and he readjusted his scarf to cover his lips and nose. The temperature hovered just below freezing.

"Right. Electrodes," she acknowledged. "What then?"

"You mean, how would I like it? Or what would I do?" Darren asked. "Or…"

Stuart shook his head. "Well, obviously you couldn't do anything. You'd have no hands, no arms, no body. You'd be helpless."

"What I meant was, how would you know?" Hillary asked.

"Well-" Darren began, but got no further. He closed his mouth again and scowled at no one in particular.

"Everything we know - everything we think we know – about the world comes to us filtered through our senses. The scientist running the machines could make you believe anything if he stimulated the right parts of your brain," Hillary expounded. Normally, she didn't talk much, but when she got started on one of her favorite topics, she could go on at length.

"Does that technology exist?" Darren asked. "Can we do that?"

"It doesn't matter. In fact, maybe the technology does exist and we just don't know it. If you're only a brain in a vat, the scientist could convince you that you're a flying squirrel or a caveman or…"

"A twelve year old boy walking to school with his friends," Stuart said quietly.

They trudged on in silence while Darren visibly struggled with the question. Stuart had covered this ground with Hillary before. They'd talked over Deceiving Demons and Brains in Vats and Realistic Dreamstates. All the hypotheticals were equally exotic – at least so long as one assumed that everything they'd ever known wasn't a lie. There really was only one conclusion to be drawn.

"I guess I can't prove that I'm not a brain in a vat, but…" Darren said at last, "I mean, what would it matter?"

"Precisely," Hillary affirmed.

"Like Minkus said, I'd never be able to do anything about it, or even realize it. I'd just keep on going exactly the way I have been," Darren concluded.

"No matter what, we still have to go on with our lives," Hillary agreed.

Stuart watched impassively; none of them asked the next question. They were comfortable with What if you're a brain in a vat?. No good would come from What if you were just a character in a sitcom?or, worst of all, What if you were just a character in a sitcom… and you knew it? It had been several months since Topanga had made her claim, and all of them were dealing with it in their own ways. Hillary had hit the books, finding her peace in the doctrines of Philosophical Skepticism. Ned alternated between denial and a fierce, confrontational brand of acceptance. Darren immediately abandoned his cape and spent his free hours obsessively watching sitcoms – ironically enough, turning himself into an average teen. Topanga remained aloof; if her revelation bothered her, she didn't let on.

And Stuart? He continued to struggle with the question. Oddly, he had not given in to the very attractive, highly feasible option of denial. He was a scientist by nature – if a claim couldn't be verified in the laboratory, it was just interesting speculation to him. The fact that Topanga had discovered the secret by feeling Cory's aura should have been laughably easy to dismiss for a rational mind like his. But he couldn't. True, he had a hard time discounting anything Topanga said, but this was something else. When he had first heard those words, he recognized them as the truth. Topanga might say that the idea "resonated with him", but he phrased it differently to himself. He accepted the Sitcom Hypothesis because it fit the facts – it answered a lot of troubling questions about the world he lived in.

The five of them made a pact, swearing not to discuss the matter with anyone outside the group. It was a sensible precaution, he felt. Cory's World (that was the title they gave the show – really, they had no way of knowing) was evidently fairly standard fare. As near as they could tell, the main characters were mostly in the Matthews family, although Shawn Hunter had been spending an increasing amount of time with the lead. The average episode seemed to run along a well-trod path; Cory screws up, Cory fixes it, Cory learns something. The sudden arrival of self-aware characters breaking the fourth wall might upset the show's producers, and it was difficult to guess how they might react. They could be hit by a bus or mysteriously vanish or… Well, there was no telling what else. That was the crux of the issue; as characters in someone else's story, they had no control over their own lives. In the end, they coined a term that summed everything up nicely: "It's Cory's World, and we're just living in it."

That day, during math class, things fell apart.

Mr. Feeny stood behind his desk at the front of the class with his hands on the back of his chair, hunched slightly forward. The teacher's eyes were a little glazed, as if he weren't the one calling the shots in his own brain. Employing unhurried, balanced words, he dictated the word problem: "Al washes a car in six minutes. Fred washes the same car in eight minutes. How long will it take Al and Fred to wash the car together?" It wasn't meant to be a discussion question. According to the instructions supplied moments before, each student was supposed to work the problem on their own. Still, Cory was in the habit of doing as he pleased.

"Piece of cake!" he declared loudly.

"Pompous ass," Stuart muttered under his breath. Feeling unaccountably irritated, he scratched at the back of his neck.

"Think about it, Mr. Matthews," Feeny warned, holding up his palm as if to halt what was coming.

"I don't have to think about it, Mr. Feeny – it's simple!" Cory said smugly.

Stuart, Topanga, and the rest of the course watched the scene unfold with practiced patience. They had each of them learned to live in Cory's World, whether they knew it or not. Mr. Feeny and Cory debated the merits of the problem for a moment, and then Cory delivered his answer with perfect self-confidence:"Seven!"

Stuart was conscious of a small tickle at the back of his head, as if someone were standing behind him with a rolled up magazine. As usual, Cory was not only wrong, but appallingly so. His mathematical effort amounted to taking the only two numbers given in the problem and averaging them. It was sickening. If Cory had stopped to think about it, he'd have realized that if Al washed the car alone in six minutes, it couldn't possibly take longer than that with Fred's help. When Cory stubbornly defended his ignorance, Stuart found he literally couldn't take it anymore.

Helplessly leaving his seat, he stood in front of the imbecile to explain: "Fred can't slow Al down! Even if Al washes most of the car and Fred just washes a hubcap, the total time still has to be faster than Al's time alone! You with me?" He used his most needling, pedantic tone, one he could scarcely avoid when talking to Cory. He went on. "So, if Fred is 25% slower than Al, then 25% of six minutes is… anyone?... It's a minute and a half! Which leaves us with four point five. Four and a half minutes is the correct answer!" He returned to his seat. "Hold your applause, please."

Then, something truly unpleasant transpired. Mr. Feeny delivered a line he never had before. "Mr. Minkus, you're wrong."

Stuart felt his heart drop. "Wrong? As in… not right?" he breathed.

"You know the law of averages better than I do. It was bound to catch up with you," Mr. Feeny said.

Stuart fumed. In his mind, he reviewed the problem. Al washes a car in six minutes. Fred washes the same car in eight minutes. Reasonably, if Fred were as fast as Al, or if there were two Als, they would wash the car in three minutes. Alternately, two Freds could get the job done in four minutes. So, clearly the answer had to be between those two numbers, and his answer of four and a half minutes was stupid – maybe not as stupid as Cory's seven minutes, but still. He felt his cheeks burn in shame. Rushing the problem and making a mistake was acceptable, but then to stand up in front of the class and lecture them so arrogantly was intolerable. If he hadn't been so worked up about stupid Cory Matthews and his stupid sitcom, none of this would have happened. Or maybe his faux pas had been scripted for him – in which case it was doubly Cory's fault.

Once again, he got to his feet, and strode toward the door.

"Where are you going?" Mr. Feeny called after him.

On any other occasion, Stuart would have turned around, apologized, and retaken his seat meekly. On that day, confronting the awful reality of living in someone else's world, he didn't even slow down. "Nurse," he said curtly, not bothering to turn his head.

At lunchtime, Stuart received a visitor. "Topanga," he exclaimed, scarcely able to control his happiness at seeing her. He loved his mother and he liked his friends, but nothing could lift his heart like the sight of his angel.

When he had shown up midmorning in the office, disheveled and frantic, no one had questioned him. With little input from him, the Nurse had found him a cot in a dark, quiet room and left him alone to rest. It was one of the perks of being a straight-A student – or the perks of being the geek character on the sitcom, depending on how one looked at it.

"Control yourself, Stuart," she admonished, lowering herself into a chair beside his cot.

Stuart frowned. Topanga didn't seem to be on the same emotional wavelength with him, but she had come to visit him when he was ostensibly sick, and that had to mean something. It had been a strange day already; perhaps it was time for some honesty. Summoning his courage, he sat upright, and swiveled around to face her. He seized her hand in his. "I love you, Topanga Lawrence," he breathed, feeling like a child who has blown out their birthday candles and is waiting to see if their wish comes true.

"I wonder if that's true, Stuart," she responded primly.

"Of course it's true! How can you question… oh."

"Yes. It's like Ned is always talking about – free will. We're all just characters in Cory's World. How can we call ourselves complete human beings, Stuart? Our bodies, our actions, our minds are not our own. You say you love me, but do you really? Or were you just written that way?"

Stuart's head drooped, and he let out a long, slow breath. "I can't give up that easily," he said after a pause. "I will keep pursuing you. I can win you over eventually."

"Suppose I said I loved you, too. Would I really?" Topanga asked. The longer she talked, the more she sounded like the girl he knew, rather than the one who sat in front of Cory in class. "Or would it just be someone else making it happen? Can you really call that love? Could that ever be enough for you? Could you settle for the lukewarm affections foisted on me by some unseen hand?"

Stuart lay back down on the cot, knowing that it was over, and he'd lost. He had no more hope for the future, no chance at happiness in a world where he had no free will, and could never even know true love.

"Stuart, did you know that I gave Cory his first kiss?" Topanga asked.

Stuart squeezed his eyes shut. "Why would you do that? And why tell me about it?"

"I don't know," she answered. "I don't know either of those things. Who knows what will happen with that? Maybe it'll be a funny story for Cory to tell years down the road, about how his first kiss was with that strange girl Topanga. Then again, maybe we'll end up married with children."

"This show can't possibly last that long!" he moaned through gritted teeth.

"No, you're probably right. How long do sitcoms normally last?" she asked. "And what happens to its characters after it ends?"

"We had a life before it started, right?" Stuart said. The strange patterns of behavior they had all noticed had started recently. They couldn't be more than a couple seasons into the show out there, wherever that was. "Maybe we'll have one after it ends. Maybe our lives will be our own then, and we can-"

"Or maybe we'll just wink out of existence," she countered. "Either way, I feel that if I stay here, I'm bound to have further romantic entanglements with Cory."

Stuart's dismay at the idea nearly prevented him from catching the peculiar phrasing. "What do you mean if you stay here?"

"Did you solve the math problem, Stuart?" Topanga asked, and at that moment her voice sounded more like it did in the classroom.

"What? About Al and Fred you mean? That nonsense?"

"I solved it in class, you know," she laughed – a throaty, full sound that was all her own. "At least, to the extent it can be solved. What kind of question is it, really? Al washes a car in six minutes, and Fred washes the same car in eight minutes. Why would Fred wash the same car? Didn't Al just wash it? Even if he did wash it again, wouldn't a sixty-second wipe down be sufficient?"

Stuart frowned. "Well, maybe they washed them on separate days, after the car had gotten dirty again."

"Well, that doesn't make much sense, either, does it? Wouldn't the cleaning time depend on how dirty the car was on the respective occasions? Maybe Al could clean it in six minutes on a normal day, but it would take substantially longer if Fred had taken the car off road somewhere. At best, you can look at six and eight minutes as expected values in a probabilistic distribution, but then you have to consider whether their combined time is literally an arithmetic summation of-"

"Wait, you changed the subject!" Stuart cut in.

"Did I? You see, Stuart, I solved the Al and Fred problem in class while you messed it up, even though you're better at math than I am," she pointed out.

"I made a mistake," he said sheepishly.

She leaned in, not close enough to kiss him, but close enough to make his heart race. "I'm sure you did, but you also failed to look at the problem from the right angle, and that's where I can help you, Stuart. I can think of things differently, and you're going to need that if you're going to solve the problem," she told him.

"Which problem? I'm not sure what you're telling me here!" he protested.

Topanga stood up abruptly and let out a long breath, as if composing herself. She gave him a small smile, and said in her best Cory's World voice: "I hope you feel better, Stuart."

He spent the rest of the school day laying in the dark, thinking it over.