A/N: The events from Sheldon's POV.
Sheldon was looking for a new roommate; his roommate of the last four years had just moved out of the state. Sheldon wasn't exactly sure why he was looking for a roommate. When he'd first moved in four years ago, he couldn't afford the rent on the place by himself; but since then, he'd gotten tenure at the college he worked at, won a Nobel Prize, and no longer needed a roommate to help pay the rent. He also didn't like people, and generally tried to avoid them whenever possible. And yet, he found himself submitting an ad to the paper looking for a roommate.
He had already had two guys come by and take a look, but both of them had left quickly once they had found out about his extensive list of rules. The third person to come look was a blonde.
He'd had no intentions of being roommates with a female, but realized that he'd forgot to mention that in the ad. But there was something odd about this woman, so instead of just telling her that he was only looking for a male roommate, that he'd just forgotten to put that in the article, he showed her around.
As he showed her around, he couldn't for the life of him figure out why he was doing so. She was the complete polar opposite of him in every way; unintelligent, messy, outgoing, and not interested in any of the things he was. And yet, he strangely wasn't completely opposed to the idea of having her as his roommate. He couldn't understand it; she should have completely revolted him, and yet here he was considering letting her be his roommate. And not just that, but at a much lower price than he would normally have asked for, since he could tell that she didn't have much money to spare.
The breaking point came when he showed her his list of rules. He expected it to send her running, since she lived in a constant state of chaos, and the strictness of his rules rivaled those of the LHC at CERN itself. What he didn't expect was for her to accept it without exception. A few quirked eyebrows, certainly, but no outright refusals. He also didn't expect, that despite the fact he could tell she had no intentions of actually following his rules, he didn't really seem to be bothered by the idea of that.
So he had offered her a lease, and she'd accepted it.
She wasn't supposed to be home this early. She was scheduled to work for another couple hours, and yet those were definitely her footsteps coming up the stairs. He froze. This was not going to go well.
She opened the door, and looked at him, and the scene around him. He waited for her panic, her scream, her attempt to dash out the door. He really had no clue what he would do if she did that. In the four years of having a roommate, he'd never been caught before.
But she didn't do any of those things. She just stood there.
Sheldon carefully edged around her, hoping not to set her off, but needing to close the door in case the neighbors upstairs decided to walk by. He walked back over to the body he'd been in the process of dismantling, and stood there, watching her carefully.
She eventually just stumbled back to her bedroom. As she passed him, he saw the half-empty bottle in her hand, and could smell the strong stench of liquor on her breath; he hoped she hadn't been driving like that. When she closed her bedroom door behind her, he breathed a sigh of relief. He knew there would be questions in the morning, but for right now he was safe.
He quickly and quietly finished his work, before returning the living room to it's immaculate condition. He would deal with her reaction in the morning, but if she did decide to call the police, there would be nothing to be found.
Sheldon was on the couch watching cartoons and eating breakfast when she finally woke up, and walked in. Out of the corner of his eye, he watched her survey the room. She finally relaxed, and moved into the kitchen to make breakfast.
He internally sighed with relief, and returned his focus to the tv. She had been nearly drunk when she came in unexpected last night, perhaps she thought it was all just some really bad dream. He would have to be more careful in the future, though; it wouldn't do for his roommate to find out what he did. He really didn't want to have to go through the hassle of finding another roommate.
It was a few weeks later before it happened again. This time, he'd decided to do his tasks while she was asleep, since she never woke up in the middle of the night. He knew better than to risk it, he really did, but she had been hanging around the apartment a lot more lately, and he was having trouble finding times when she would be out for long enough.
As soon as she rounded the corner of the hallway, he could feel her eyes on his back. He could also smell the faintest traces of alcohol on her breath, and figured she was finally paying attention to some of the wealth of scientific advice he so graciously passed on to her on a regular basis, and was coming in to get a cup of hot tea to reduce the impending hangover. She really needed to stop drinking so much.
He could hear her freeze, turn around, and sneak back to her bedroom as quietly as possible. He was going to have to talk to her in the morning, even if she didn't bring it up first. She was a nice girl, even if she did drink and party too much, and he didn't want to see her any more psychologically scarred than she was already guaranteed to be.
When he heard her walk in, he decided to take the initiative, and casually asked, "Decide you didn't want any tea after all?"
He could feel her tense up without ever needing to look at her.
"Um, yeah. Stomach got a little upset when I got in here."
Was she trying to pry more information out of him, or was she trying to pretend like it never happened? He could barely understand her at the best of times, when she was being straightforward and blunt; he certainly couldn't read her now.
"That's understandable."
That had to be a sufficiently vague answer, didn't it? She could take the conversation wherever she liked from there.
It was a few seconds before she said anything else.
"So, uh, I really like being roommates with you, but I've been thinking, and perhaps it's time I moved out and moved on with my life. This whole California thing isn't really working out."
So now she was starting to panic. She'd finally accepted what she'd seen, and was trying to find a way to escape without alerting him.
"Don't worry, I would never hurt you."
He wasn't sure why he said it. Why he didn't just tell her she was free to go, he had no intentions of trying to keep her here because she knew his secret. But she was talking again before he really had time to think about it.
"Um, it's not really that. Well, I mean, it's not just that, because it definitely is that, but it's more than just that."
He finally looked up, and looked her directly in the eye. "But it has nothing to do with 'California not working out'." He knew it to be a fact, he just wanted her to admit it to herself.
"Well, yeah."
He looked back down at the newspaper he'd laid on the island. "You're of course free to move out if you'd like, but I would never hurt you."
"It's not about you hurting me, it's the fact you're still—"
He could tell she was starting to get angry. Her voice rose, and then died as she didn't know what to say. That was certainly a reasonable response. He wasn't proud of what he did, and he knew it was certainly wrong, but he couldn't stop himself. So he just used it in the best way he knew how.
As the silence lingered on for a few awkward seconds, he decided to come straight out and lay everything on the line. That way, she'd at least know what she was dealing with.
"I'm a psychopath who kills rapists who slide through the justice system. As a physicist, I can do so without ever getting caught." Except by my roommate, as it turns out," he added in a mumbled undertone. She started to say something, but he cut her off; he knew what was bound to be going through her mind.
"And before you think about going to the police, they will never find any evidence, and it would just be the word of a waitress who drinks too much versus the word of a prominent theoretical physicist with a Nobel Prize, who, while being antisocial and a narcissistic egomaniac, has never shown any violent tendencies."
She choked out a stunned "Oh."
He watched her carefully, seeing the wheels spinning in her brain. As she struggled with what she knew she should to, to beginning to have an understanding of why he did what he did. As he watched her think, he wondered if she'd been personally affected by the types of crimes he was attempting to punish, and prevent. Then he saw her thoughts return to the topic of whether she would, or even could, stay.
He could see the resignation the instant it settled on her face and in her eyes, even though her brain hadn't accepted it yet. A small smile playing on his lips, he grabbed his cereal bowl and started around to the sink, and gave her the answer she couldn't say herself; "It's pizza and Mario Cart night. Don't be late."