Lisa's office resembled army headquarters during a battle: her PA was yelling into his phone, harried nurses rushed in and out, physicians hung around hoping to get a last signature on some form or other. In the midst of it Lisa could be heard shouting instructions.

"Toxic substance!" Pete yelled, pushing Rachel's wheelchair into the melee.

The crowd made room, mostly because Pete had no compunction about bumping the wheelchair into people's shins. When Lisa spotted them, she enveloped Rachel in a warm hug. Pete retreated the way he'd come; this touching family reunion could progress without him, the transplant not so much. Chase had sent him a sum total of six text messages over the past twenty minutes, messages that he'd ignored so far. It was safe to assume, however, that preparations for the surgery weren't progressing in the manner that Chase desired.

It didn't take him long to find out what the problem was. He ran into Chase in the corridor outside Lisa's office.

Chase pulled him to one side. "Why the fuck didn't you tell me that it's Cuddy who's donating?"

Pete scrutinised the tips of his sneakers. "When we discussed it I didn't know for sure. It makes no difference, anyway."

"Makes no difference? She's half his size! We'll need to take the entire right lobe of her liver!" Chase looked around the corridor as though checking out escape options. "I'm not doing it."

"Don't be an idiot! You didn't object to operating on Wilson. She is less likely to die than Wilson, no matter how much of her liver you take."

Chase's face stilled. "Don't try to mess with me, House. If we keep our fingers out of Cuddy, there's no chance of her dying."

"If you don't take Cuddy's liver, then Wilson's chances of survival are nil." He exhaled impatiently. "Take as much of her liver as you can justify; Wilson will just have to take his chance with what he gets."

Taub came up looking harried. "The surgical staff want you at the prep meeting," he said to Chase. "Have you talked with Cuddy?"

"Yes, she said she's fine with donating, knows all the risks, etcetera, etcetera," Chase said, glowering at Pete.

Pete stared right back. "Then everything's just hunky-dory, isn't it?" he said.

"Only if Wilson is her boyfriend for real."

Pete grimaced. Lisa's staff were a lot more credulous, probably because they had no reason not to believe him. "Is he such a bad choice for her?" he asked.

"No," Taub said. "That's the point: she isn't exactly known for sensible choices."

The part of his brain that was responsible for affect control indicated that if it didn't get a drink soon it would implode. "So, your only objection to the procedure is that Lisa is finally dating a guy who is good for her?"

"No, it isn't. This is a bloody nightmare," Chase said. "We can't ask Wilson what he wants, and it turns out that his medical proxy is also our live donor."

Pete gave them his best 'duh' look. "That tends to be the case when partners are live donors, doesn't it?" he said.

"I've got a bad feeling about this," Taub said.

His affect control gave a friendly wave and made for the emergency exit. "You're gonna let Wilson die because you have a 'bad feeling'?" he said, sketching the quotation marks with his fingers. (Judging by the heads turning his way, he must have gotten a bit loud.) "Do you subject all your donors to an evaluation of their relationship status or is that a luxury reserved for my patients?"

The two men were silent.

"You've got Lisa's signatures on everything, she's healthy as a horse, and I take it that she passed the psych test. The rest is, None. Of. Your. Business! Go to your prep meeting!"

They moved off stiffly, their body language indicating their reluctance. He watched them until they rounded the corner, and then turned his attention back to Lisa's office. Lisa was kneeling in front of the wheelchair clasping Rachel's hands while Rachel looked confused and unhappy.

An OT nurse hurried past him towards the anteroom where Lisa's PA sat. "We need Dr Cuddy to get prepped for surgery," she said.

"I don't think she's ready yet," the PA said, showing no indication of interrupting Lisa's mother-daughter bonding session.

"She was supposed to have been down in the prep room twenty minutes ago," the nurse said.

It didn't look like either of them were likely to end this stand-off they were in, so he pushed past them and poked his head into Lisa's office.

"Need you," he said. "Get your neighbour to pick her up from here."

"I can't reach Louisa," Lisa said, while Rachel wailed, "Can't I sleep at home? I don't wanna sleep at Louisa's!"

Lisa turned back to her. "Honey, you're eight; you can't stay by yourself."

"What about Emma?"

"Not for a whole week; that won't work," Lisa said, looking stressed out of her mind. "This is ridiculous! Getting someone to run this hospital while I'm on sick leave is easier than getting Rachel fixed up for a week."

"Send her to your sister's," he said, tapping an impatient rhythm on the glass door.

Lisa bit her lip. "I don't think I want to explain this to my sister until it's a fait accompli," she said. She had a point there: getting the Cuddy clan to consider this a good idea would take longer than Wilson had time.

He puffed out a long breath of air. "I'll fix something. You go get prepped," he said.

Lisa looked at him quizzically. "'Something'?" she repeated.

"Yeah. If Louisa doesn't turn up, I'll call Tanja," he said. "The Russian nurse," he added when Lisa looked blank.

"Oh, her," Lisa said disparagingly. "That'll work great – a woman who can't speak a word of English!"

He stared hard at her; she stared back. Finally she threw up her hands. "Okay. Just make sure there's always someone in the house when Rachel's there. She has physio on Tuesday after school, swimming on Thursday …"

"Swimming?" She had to be kidding.

"Yes, but I guess she can skip that, and she can certainly skip her Orff group. But she needs to go to physio again on Friday."

His expression must have given him away, because Lisa said, "She's attending her physio sessions, Pete. Those are not up for debate." She looked at Rachel. "Are you okay with Pete looking after you?"

Hang on, that wasn't what he'd offered!

Rachel examined him critically, and then nodded her head. "Yeah, Pete's okay."

Wow, what an endorsement!

Lisa bent down and gave Rachel an enveloping hug. "You can come visit me as soon as … as the doctors say it's okay," she said.

"Can't I stay here till after the operation?" Rachel asked, showing first signs of unease.

Lisa hesitated. Pete shook his head at her. There was a risk of complications and Wilson's chances of surviving the procedure were slim, to put it optimistically. Lisa nodded that she'd understood. "No, I'm afraid not," she said to Rachel. "The operation won't be over till the middle of the night and I'll be groggy for hours after that." She turned to Pete and jerked her head towards the door. The message was clear: Get her outta here before she makes a scene.

"Then let's go," he said. If he got hold of Tanja or the elusive Louisa, he could be back in time for the operation.

As they left the room, he could hear Lisa on the phone again: "Yes, Arthur, I know this is difficult and an imposition, but you owe me."

Rachel was silent all the way to the car. Once she was strapped in she said, "What does the liver do?"

"It cleans the blood."

"Oh. Can Mom's liver still clean the blood if half of it is gone?"

"Yeah, it grows back almost to its original size."

"And if Wilson gets Mom's liver, he'll be okay?"

He considered the impact of an honest answer. No, chances are that either Wilson's body will reject the liver or that he'll die of an infection because his immune system is weakened. Or, if he's lucky, he might survive for long enough to die of cancer. But hey, let's cut up your mother anyway! Not really an option.

"It's a start," he finally said. "Once he has a functioning liver again, we can do something about his tumour." That was, if his tumour had shrunk sufficiently.

"And Mom's really going to be fine?" There was a plaintive note in her voice that he had never heard before. Rachel demanded, whined, and sulked with the best of them, but he'd never seen her confidence in life shaken.

He risked a sideways glance at her. "Yeah, the operation is practically risk-free for her. But she'll be very weak until her liver has re-grown to its original size."

When they reached the house in Germantown no one answered the door at Louisa's place.

"It's her book club afternoon," Rachel said. "She won't be back anytime soon." There was no mistaking the satisfaction in her voice.

He opened the door to Lisa's place with the key she'd given him and gestured to Rachel to enter while he pulled out his cell phone. Tanja was willing to help out once he'd sold her Rachel as a medical challenge, but no, she couldn't stay overnight; she had children of her own and had to leave at nine every evening. He supposed those had been her conditions when helping with Wilson, but he hadn't taken much notice because he'd had no intention of leaving Wilson for the night anyway.

"Will Louisa be back by nine?" he called to Rachel, who had gone straight into the kitchen.

"I don't wanna go to Louisa's place!" came the answer.

He went into the kitchen. The fridge was open and Rachel was in front of it, but whatever she was trying to get out was too far back for her to reach, and no leaning out of her wheelchair would change that. He really couldn't leave her alone, he supposed. She'd starve with a full refrigerator in front of her.

He fished out the yoghurt she was angling for and plonked it on the table. "Here," he said.

She wheeled back to get a spoon out of the silverware drawer. He waited until she tore the tin foil off the yoghurt cup and started eating.

"Look, I need to go back to the hospital," he said.

She glowered at him. "I'm not going to Louisa's," she reiterated.

"If I say you're going, then you're going."

"Can't I go back to Lucas and Cheryl?"

He'd need all of four hours to get her there and himself back, and he doubted they'd take her without Lisa's implicit instructions. Lisa, however, would be in the midst of the prepping process by now or being wheeled into the OT already. He wanted this fixed quickly so he could get back to the hospital. He'd leave her here with Tanja as soon as she came if he could be sure that Rachel would go to Louisa's place before Tanja left for the night. But if Rachel played up, how would Tanja, with her non-existent English, explain the situation to Louisa and get Rachel to budge?

"Tell you what," he said. "If you agree to go to Louisa's place tonight, you can sleep here tomorrow night. I'll stay then."

Rachel eyed him shrewdly. "And the night after. And the one after that. I don't want to go to Louisa's for the rest of the week, then."

"No way!" he said. "One night, that's all."

"Louisa's got her bridge club on Tuesday night and dancing on Friday night. She won't want me on those nights anyway," Rachel said with the air of someone playing a trump card.

Her mother must have some other babysitter at hand, he figured. There was no way Lisa could always avoid engagements on Tuesdays and Fridays, not with the two jobs she was working at the moment. Of course, for the past few weeks Wilson had been at her disposal, ready to cook for, play with and read to her little monster …

"All you need to do is sleep here instead of downstairs," Rachel said in cajoling tones. "I won't bother you and I'll eat anything you cook."

He had no intention of cooking: there was takeout and Tanja could cook. But other than that she had a point. His plans for the coming week didn't feature anything that required his presence after nine p.m., so there was no reason why he shouldn't loll in front of Lisa's television instead of Wilson's. If something did come up – an emergency at the hospital, for instance – he could still organise someone for Rachel. If all else failed, he'd pay Lucas Douglas to come and babysit.

"Okay," he said, "it's a deal. You go to Louisa's place when she comes back, and in return you can sleep here for the rest of the week."

Rachel whooped with delight; he'd probably caved too quickly, he figured, but with a bit of luck her gratitude would make her generally amenable. She was still in such a good mood when Tanja arrived that she accepted the presence of a babysitter whose English was rudimentary at the best without batting an eyelid. Tanja tutted at the state of the fridge, accepted his offer to order takeout ungraciously, and generally put on a martyred air when she realised that he was about to leave her alone with a child who didn't understand her, but all that was easy to ignore. He wrote a note for Louisa, pinned it to her door, and went back to the hospital.

It was only when he got back that he realised he had no plan. He was a nobody; he had no official medical status that could help him get at information, let alone enable him to watch the procedure itself. He wasn't a family member of either party, so no one felt obliged to keep him updated. Chase or Taub might have done so if they'd had the time, but Chase had to supervise both procedures, the removal of Lisa's right lobe and its implantation in place of Wilson's liver, so there was no chance that he'd think of him, Pete.

He sat on a bench in front of the operation theatre area, kicking his heels and hoping that someone who came out would update him, when he realised that traffic was all in the other direction. A liver transplant – and with a live donor at that – was a sensation, so everyone at the hospital who had the time and a smidgen of an excuse was on a pilgrimage to the OT where the procedures were taking place. Finally he gave up and made his way to the ICU.

Liu was at the nurses' station going through some files. He leaned on the counter, folded his hands in front of him and rested his chin on them, gazing up at her wistfully.

She narrowed her eyes. "Shouldn't you be somewhere else?" she asked.

"No one wants me!" he said theatrically.

She straightened and jerked her head towards the door of the ICU. "Come on," she said.

When they reached the second floor she opened the doors to the OT area with her card and led him in. There was a staff room off to one side that she opened too. "You can wait here," she said. "The OT teams come in here for their breaks. Don't get on anyone's nerves!"

"Can't I watch from the gallery?" he whined.

Liu raised her eyebrows. "What gallery? We've got windows looking in on the operation theatres, but half the hospital will be crammed in front of them hoping to catch a glimpse of the procedure. You'll get thrown out in no time if you go there."

The room sported two shabby couches, a few armchairs, a shelf with discarded books and antediluvian magazines, a small television, and a coffee machine. He ensconced himself in an armchair with a pile of National Geographics and waited.

The first to come in were nurses and anaesthetists who'd ended their first stint in the OT. Pete did his best to look nondescript, willing himself not to gain undue attention as he listened to babble that mostly centred around the novelty of helping out during a live donation. A few doctors drifted in and out: lurkers from other departments, discussing the risks of the procedure, the advisability of Philadelphia Central doing it, and assessing Chase's competence.

It seemed that so far nothing dramatic had happened.

"We'd agreed on sixty percent of the liver. He took out seventy!"

Pete, who'd been nodding off from sheer boredom, started upright. A bigger group of surgeons and surgical nurses in scrubs had entered the room, straight from the OT by the looks of it.

"He's an experienced surgeon," someone else said. "He knows what he's doing."

"He's a former colleague of Dr Wilson's. He's saving his friend at the cost of the donor, who happens to be our dean. It's unethical, and it's not what we agreed on!" The surgeon who was talking slammed a cup under the coffee machine and pressed a button. The whirring and grinding of the machine swallowed whatever else he was saying.

So Chase had taken as much of Lisa's liver as he could. Pete felt a cold shiver along his back. It was true that live donations were unlikely to be fatal for the donor – but that was because in most cases they were parent-to-child donations where less than half the liver got transplanted. Seventy percent was … pushing it. Pushing it pretty hard.

He thought of Rachel back in the apartment in Germantown, confident that her mother would be fine because he had said so. He thought of Chase taking out more of Lisa's liver than was warranted, because he had egged him on. He thought of Lisa, whom he had convinced that it was her duty to save her friend since the cost to herself was limited.

Shit. Shit. He'd fucked up big time.

If Lisa died, he'd have killed her, ruined Chase's career, and made an orphan of Rachel. And if Wilson died too, it would have been for nothing. He'd been so focused on disentangling the mess Wilson had gotten himself into that he'd lost all perspective.

He wished he were stupid enough to believe in a deity. You could pray to God, dump the fuck-up you'd caused on him, and then sit back expecting him to clean up the mess. If he didn't, well, then that meant that he wanted things that way and that you'd merely been the tool he'd used to achieve his aims. What a wonderful way out for all fucked-up, stupid egomaniacs!

There was no such way out for him. If Lisa died, he'd never be able to atone for it.

The irony of it struck him. He'd given up his identity in a fit of disgust and loathing, triggered by a deed that had cost no lives and had seriously injured only himself. What act of cleansing would murder, caused by hubris disguised as friendship, require?

He staggered up, ready to flee the hospital, when Taub and Chase entered.

It was like the sea parting for Moses: the hubbub died down, everyone made room, those closest to the door exited discreetly. Chase collapsed on the nearest couch and sprawled along it, muttering, "Fuck! Oh, fuck, fuck!"

Pete's heart stopped.

Taub moved to his side and placed a hand on his arm. "Everything's fine. Cuddy is stable; they're removing Wilson's liver at the moment, and we aren't needed. Chase just needs a break – we have another five hours to go at the very least."

He stared down at Taub, processing his words. "How do you define 'fine' and 'stable'?"

Taub's face was expressionless. "Everything is going as planned."

Pete moved over to the couch, looming over it. "They say you took seventy percent of her liver," he said, not bothering to keep the menace out of his voice.

Chase cracked an eye open. "Chill, House," he said wearily. He struggled to pull himself upright.

Everyone in the room was looking at them.

"Someone get me a cup of coffee," Chase said. Three people promptly jumped. He rubbed a hand across his face and then tugged it through his hair, which could have done with a cut. "And an aspirin."

"You'll kill her. Correction: you have killed her." He wanted to shake Chase or deck him, but if all this was to have a meaning, Chase had to save Wilson, so injuring him was not an option.

Chase gazed at him calmly, but not unkindly. "Wasn't that what you wanted? As big a chunk of liver as possible?"

He cast around the room, looking for something he could focus on before he lost it entirely, started yelling, and got tossed out of the OT area. "What I want and what you do …," he began.

"Chill," Chase repeated. "I did what I did because I decided it was medically justifiable, not because you asked me to do it. I'm a big boy now; I can make my own decisions. She's in excellent health. I've had patients where even half of what I took from her seemed risky in comparison. There's no sense in taking any of her liver if it isn't enough to see Wilson through. It's all or nothing, House. Taking a pinch of liver here and another one there isn't going to get us anywhere, and Wilson doesn't have a second chance."

He smiled a thank you at the person who brought him coffee and an aspirin, tossed the aspirin in his mouth, and washed it down with a big gulp of coffee. Then he rolled his shoulders and stretched, causing his joints to crack alarmingly.

"Go home," he said. "There's nothing you can do here, and Wilson will need you more when he comes around than he does now. Come, Taub, we need to scrub in again." Nodding to Taub, he went out of the room.

Taub gave Pete what was probably supposed to be an encouraging pat on the arm, but which came over like a petrified boy trying to pat a huge, grim dog without getting his fingers bitten off. Turning to the room at large he said, "Keep this man supplied with candy bars; he's obnoxious when he's under-sugared." Then he followed Chase out into the harsh green corridor.

Everyone was still staring at him. To terminate all conversation he dropped down on the couch that Chase had just vacated and stretched himself along it, closing his eyes and draping his arm across them to shut out the light.