House always wanted to break into Foreman's place.

He had waited for the opportunity. He had kept tabs on schedules, had checked Foreman's daily planner, had accessed phone records; his eyes had been peeled. Not without effort, House had hacked into Foreman's e-mail, discovering a receipt for one first-class plane ticket to Chicago and one panelist confirmation notice for the International Conference on Alzheimer's Disease. In his consuming quest for information, House had almost overlooked Foreman's sudden onset of respiratory symptoms; the realization, when it struck, had made the B-and-E all the more urgent. Now he had a mission.

As House stepped inside Foreman's apartment, he held his phone to his ear. "See what happens when you keep secrets from me?" House asked Foreman. The din of Newark International crackled with static and leaked into House's ear.

"I don't have to tell you everything," Foreman countered coolly.

"No," House conceded, "but I'll find out anyway." He shut the door hard enough to make sure Foreman heard it through the phone. "You're sick."

"And you felt the need to break into my house because you're"-Foreman trailed off for a moment before he guessed-"bored? No patient today?"

House strode into the kitchen, reaching the sink and studying it. He lowered himself to one knee. "You haven't given me a key yet," House said, injecting as much over-the-top disappointment into his voice as he could summon. "And you're sick." He opened the cabinet to peer under the sink. A scan of the plumbing revealed nothing but white, spotless PVC. Grunting, he got to his feet. "I think there's an environmental cause."

A puff of air crackled at the other end of the line. House imagined Foreman's steeled expression, jaw set, brows arched but furrowed. "House, get out," Foreman demanded, his voice as low and authoritative as infected sinuses would allow.

"Huh," House mused, strolling through the warm, terra cotta tones of Foreman's living room, eyes browsing the ceiling. "Three days ago, it seemed like you wanted me here. I remember being hustled through the hallway by my-"

"I was there to supervise," Foreman spat. "I'm serious. Get out."

"Oh, you're serious? It's hard to take you seriously when all your 'T's sound like 'D's." He smirked, letting his expression filter into his voice. "You're going to sound great for your panel presentation."

Foreman responded with a strained sniffle; House was certain it was accompanied by an eye roll. Following another burst of breath, Foreman said, "It's not environmental. If it was, my symptoms would be gone."

"Not yet. It could take another day or two for the toxins to clear your system."

"My place is clean! No toxins. No fungus. No radioactive waste."

House pushed open the door to the bathroom. He hooked his cane around the doorknob and kneeled beside the pedestal sink. "Well, radioactive waste might explain a few things. Your extra toe. Your huge-"

"Was it you"-As Foreman interrupted, House jerked the phone away from his ear to glare at it-"who said that happier patients recover faster?" Foreman paused. If Foreman had been in the room, House would have been staring at the tip of a pointed finger. "Nah, couldn't have been."

"I said that studies indicated that happier patients recover faster," he refuted, levering himself to stand. He tottered across the room and peeked around the shower curtain, into the bathtub. "And I was about to say 'huge ego', by the way."

Predictably, Foreman dismissed House's last remark. "Yeah, well, I'd be ecstatic if you would get the hell-"

"Don't care," House said, his eyes sweeping the walls. "I'm not trying to make you happy. I'm trying to find the cause of your symptoms."

"Oh, you know what? You're right," Foreman said, sarcasm oozing through the phone. "Oh, wait. I already did that. It's a cold, House."

"Nope! You've been fatigued. You've had headaches. Sinus problems."

"Uh, yeah." Foreman laced his sarcasm with arrogance. "All symptoms of the common cold."

"The other day, when you raced me to the patient's room, you took the stairs. When you finally showed up, you were out of breath."

"So I'm a little out of shape."

"You were wheezing. You're not that out of shape. You're sick." House craned his neck, inspecting an air vent above the toilet. He stretched to swipe the cover with his finger and frowned when he found nothing on his skin but a thin layer of dust.

"You're not going to find anything," Foreman said, "except maybe a few garbage cans full of used tissues."

"You get horny when you're sick? Weird. Don't expect me to swap any spit with you until I figure this out. Or anything else." House drowned out Foreman's put-upon sigh as his eyes fell on the toilet. He tilted his head, squinting his eyes; he could feel the epiphany swirling at the back of his brain. As he flipped the lid, his lips stretched with a satisfied grin. "Oh, Foreman?" he singsonged.

"What?" Foreman gritted.

"You have a visitor!" House dropped the singsong, but the amusement remained in his voice. "You have mold on your toilet seat. How could you not notice that?"

Foreman's tone changed from irritated to incredulous. "What? No, I don't. There's no way-"

"I could send you a picture."

"No, it's-no. I don't study the seat before I sit down to shit," Foreman justified, his voice leaping up an octave. He sounded disgusted.

"Maybe you should," House said, bending over to study the growth. Black mold spread like twisted tree branches over the seat, wrapping around the edges. "I always like to know what comes into contact with my ass. Don't you?" House pulled a Petri dish from his pocket and scraped a sample from the seat. He carefully set the dish on the edge of the sink and closed the toilet.

Surprisingly, Foreman didn't take advantage of the chance for a snappy comeback. "Wait," he said instead, "How did you not notice? You've used my toilet."

"Not to take a dump." House shuffled across the room to investigate the linen closet. "No reason I should have noticed." When he peered into the closet, he honed in on a water stain the size of a dinner plate in the corner of the ceiling. A black patch of mold spanned half of the stain. "There you are," House whispered, pointing to it.

"There what is?"

"Water stain in your closet. Mold's all over the place. Looks like it's settled in, raised a family, spreading joy and mycotoxins where'er they go." House backed away and shut the closet door.

Foreman sighed, sniffled, but didn't speak-no argument.

"It's probably Stachybotrys," House continued. "I'm guessing it's been there for a while, since you're showing symptoms."

Foreman was quiet for a moment before he finally huffed and said, "I have to board. Get out of my house."

House leaned against the sink, crossing his right ankle over his left. Before he heard the line disconnect, he shouted, "Just so you know, we're going to my place from now on!"