The house, the Sea Cottage, isn't big. It's painted white, with a reddish brown roof, like almost every other house he's come across in the distance he's walked from Pallet. It's ordinary, so he only glances, before walking in.
It's like stepping into another world, and Yellow has to blink several times to make sure he isn't hallucinating. The interior of Bill's house is polished and precise, a lab almost comparable to Professor Oak's. The computer sitting on a desk in the center is top-of-the line, a model he's never even seen, and there are two enormous, complicated-looking machines in each back corner of the room.
Something is standing in the center of the floor. Pikachu scampers up to it, looking puzzled.
The thing doesn't attack, so Yellow thinks it's safe to approach. He thought it was just a pokémon at first, but Pikachu is still looking at it quizzically, so he thinks he'd better take a closer look.
As soon as he's close enough to properly see the thing, Yellow screams. It looks like a Nidorino that someone pulled apart from the seams, with splotches of pale skin layered across its body randomly. Its proportions are all wrong, it's too tall and not properly wide enough and it looks as though it's about to collapse. It's obviously in pain, trembling, but its face is smiling and Yellow is terrified because Nidorino don't smile.
"Hiya!" it suddenly exclaims, and Yellow shrieks and jumps back. The Pikachu cries out as well, looking terrified.
"Oh, wait, I'm not," it continues, its voice warped and awful, before it is suddenly overtaken by a coughing fit. He and Pikachu watch, frightened, as it struggles to stop, blood dribbling out of its deformed mouth. The thing can't properly lift its arms to wipe it away. After a moment the coughing passes and it splutters out, "I'm Bill. I'm Bill. You've got to believe me, I'm not a pokémon."
Of course he isn't. Yellow nods, unable to speak. He wants to grab Pikachu and run, but the thing—Bill needs help.
"It was an experiment," the not-pokémon rasps weakly. "I screwed up an experiment and combined myself with a pokémon. Please, just run a program on my computer and I can fix it."
Yellow nods again, unable to think of what else to do. He glances at the computer with a bit of trepidation. He's never even used a PC before.
"Just run the Cell Separation System as soon as I get in the teleporter," says Bill, grateful, gesturing towards one of the giant mechanical cylinders. At Yellow's nervous look, he adds, "It's the default option." He smiles again, making him look like a nightmare monster, before staggering to the cylinder, which opens to let him in and closes as soon as he enters. Pikachu runs after, staring at the machine with bafflement.
Shaking, Yellow approaches the PC. Initiate? a text box questions over a series of complicated programs. He clicks the 'yes' button on the screen and the room is filled with noise, screeching and whirring that makes Pikachu grimace and cover its sensitive ears.
After several minutes a man stumbles out of the opposite cylinder. He's fairly tall, with black hair and nondescript clothing. Ignoring the hyperventilating Pikachu he approaches Yellow with a relieved grin.
"Yeehah! I owe you one, bud! That could have ended pretty badly. Hey, do you want this ticket for the S.S. Anne? I'm not going to—"
"Where is it," Yellow interrupts, his voice flat. His eyes are glued to one of the machines at the back of the room, not the one Bill just came out of, but where he went in the first place. The Pikachu has calmed down, and its ears prick as it hears something unusual in Yellow's tone.
Bill looks confused. "The ticket? I've got it right here, here you go—"
Yellow turns to face him so quickly he hears something in his neck crack. "No! The pokémon, where is it?"
Bill's grin falters. The Pikachu is concerned at the panic in Yellow's voice, and approaches swiftly, tugging at the fabric of the boy's jeans. He ignores it for the moment.
"Tell me," Yellow demands, shaking again. "Where's the pokémon." Bill doesn't answer, looking frozen, looking like he can't think of how to answer. He's at least a foot shorter, but Yellow seizes the man's shoulders and digs his nails into the fabric of his shirt. "That machine was supposed to separate you from the pokémon. I ran the program because I thought it would separate you from the pokémon. Where's the pokémon."
When the PokéManiac still fails to respond Yellow shoves him backward and runs to the right cylinder. Bill regains his balance and shouts a protest, trying to give chase, but the Pikachu finally understands what's going on and throws himself in the man's path, cheeks sparking furiously.
Yellow knows he doesn't have to look. He knows what's in the machine. But he also knows that if he leaves he might trick himself later into thinking that it was all a misunderstanding. He knows, but he has to know. He throws the entrance to the machine open and screams at the bloody remains of the Nidorino. He flees the cottage with Pikachu at his heels, ignoring Bill's desperate shouts behind him.
Once outside, Yellow stumbles to the edge of the aesthetic pond in the front and vomits until he can't anymore. The Pikachu watches the cottage behind them warily, through glazed eyes, but Bill doesn't come out of it.
"I will never use his PC," Yellow mumbles, wiping his mouth. Pikachu nuzzles his chest affectionately and he reflexively wraps his arms around it. "Never, Pikachu. I promise."
He stands with the pokémon in his arms and begins the slow walk back to Cerulean City.