A/N: Part Four of the Psycho Sheldon Trilogy

"Penny, do you honestly believe you could ever actually consider marrying me? Knowing what I do, who I am."

Penny looked up from her cereal. It was the morning after their discussion, and they hadn't talked about it at all since then. They had gone to play mini-golf, and ended up catching the latest Marvel movie afterwards, but the topic of relationships had not been breeched, and they hadn't discussed a day to go out on their date.

The question caught her off guard, and it took her a few seconds to respond. She didn't want to lie to him, but she also wanted to be encouraging.

"Honestly, sweetie, I don't know. I've accepted that my roommate kills bad guys, but whether or not I could marry you, I don't know yet. But that's not going to keep me from dating you, and finding out."

Sheldon, who was still staring at his oatmeal while he absently stirred it around, just nodded slightly.

"If it makes you feel any better, I really enjoyed yesterday," added Penny, hoping to cheer him up at least a little bit.

Tuesday night was turning out to be a drag. There weren't a ton of customers, and the ones she did have were mostly obnoxious, inappropriate, and didn't tip worth a darn. Penny had just finished her break when the hostess hurried up to her.

"This guy is insistent on being seated in your section. What do you want me to do?"

Penny glanced over at the entrance, and saw Sheldon standing there.

"Oh, he's fine," she replied. "You can seat him in my section."

The hostess hurried back to where Sheldon was standing, leaving Penny to wonder what her roommate/boyfriend was doing there. He'd never come to eat there before; in fact, as far as she knew, he never ate out anywhere.

"Hey Sweetie, what brings you here?" Penny asked as she walked up to his table.

"If I am to have to accompany you on a date," he replied stiffly, "I thought it prudent to accustom myself to eating at restaurants I am not used to."

"Awe, that's nice of you! Well, do you know what you want?"

Midway through his meal of a barbecue bacon cheeseburger, barbecue, bacon and cheese on the side, three beefy guys were sat at the table in front of Sheldon. Distrusting them immediately, Sheldon kept a wary eye on them as he finished his meal. When Penny came up to take their order, all three of them made attempts to grope her, along with making inappropriate comments to her.

Sheldon had long since finished his meal, but he continued to sit there and watch them, growing more irritated by the minute. After about the fifth time one of them tried to grab Penny's butt, he stood up and walked over to the table, and planted himself in front of them.

"Your inappropriate attempted physical contact with your waitress is unacceptable, as is your speech. Kindly refrain from doing so anymore."

"Oh, and who exactly do you think you are, huh?" said the tallest of the three. "The inappropriate touching police?"

All three of the guys burst out laughing with great guffaws. Sheldon continued to stare at them impassively.

"Someone you don't want to mess with. So leave my girlfriend alone, or you will regret it."

"Are you threatening us, you skinny little twig?" replied the biggest of the three, standing up to face Sheldon. He had two inches and at least 100 pounds on Sheldon, but Sheldon stood his ground.

"You were warned," he replied, before spinning on his heels and returning to his seat, and giving them a death glare until they left. The three guys refrained from attempting to touch Penny for the remainder of their meal, though they continued making inappropriate comments whenever they had the chance.

After they left, Sheldon payed for his meal, and left as well. As Penny cleaned up his table and looked at his bill, she was surprised to see how much of a tip her roommate had left her. For someone who already payed well over half of the rent on their apartment, along with all the utilities and most of the food, he tipped her really well.

When Penny returned to the apartment that evening, she collapsed onto the couch, and watched Sheldon mull over his whiteboards for a while. It had been a long day, and her feet were too tired to move her any further.

Just as she had worked up the energy to head to the kitchen to try to find something to eat, a plate appeared on the coffee table in front of her. A second later, the lanky physicist sat down in his seat next to her, handing her one of the two tea mugs he was holding.

Looking over at him, she gave him a weary smile and a tired "thanks" before digging in. After she was about halfway through, and no longer starving, she looked back over at him. He was absorbed in some science magazine of his, and if he noticed her, he didn't show it.

Clearing her throat slightly, Penny said, "Sheldon, I appreciate you for standing up for me at the restaurant tonight, but you really didn't have to. I'm used to it. It's just part of the job."

He turned and looked at her. "Just because you are used to it, doesn't make it right."

"I know, sweetie," she replied, patting him lightly on the arm, "but just don't go kill them because they tried to grab me, okay."

"Penny, I don't just randomly murder people because I dislike them, or they do something wrong," he said sternly. "They have to really deserve it, and not have already served a sufficient punishment for their crime. Anyways, I strictly deal with rapists. Assault is not my area."

At this, he stood up and returned to his whiteboards, leaving Penny with her own thoughts.

So he's not the only one around who deals with bad guys that fall through the cracks.

Thursday evening, Sheldon and Penny left the restaurant where they had just finished their first date. Penny had found a cute little Italian restaurant within walking distance, and after much grumbling, Sheldon had finally agreed.

Walking out of the restaurant, they began the pleasant stroll back to the apartment. As they passed a dark alleyway, they suddenly found themselves being grabbed by strong arms and pulled into the alley. Penny and Sheldon were pulled apart, and strong hands covered their mouths to keep them from making any noise. They were dragged deep into the alley, and into a cross-alley completely hidden from the road, behind the buildings, where there was some light.

Now that they could see, Penny and Sheldon saw who their attackers were; the trio from the Cheesecake Factory two nights before. The tall one held Sheldon, while the shorter one held Penny, and the biggest one stood in between them.

"So," the big one began. "Thought you were all threatening at the restaurant, didn't you, you little twig? Not so big now, are you? You see, I happen to have a taken a liking to your little girlfriend here, and you interrupted me from getting a fair shot at her. So now I'm going to have to take her the hard way; for you, that is. See now, instead of me just charming this pretty little thing into my bed, and then giving her back to you, I'm going to make you watch as I have my way with your precious little girlfriend here, and then leave both of you beaten up back here. If you survive, and still want her, then she's all yours," he finished with an evil chuckle.

Turning his back on Sheldon, he walked over to where Penny was being held. Just as he went to grab Penny's skirt, he heard a sharp cry from behind him. But before he could turn around, he felt a knife being pressed to his throat.

"Don't move, or I'll slit your throat right here and now," he heard growled into his ear. "Thankfully you picked a very secluded location, making my job that much easier," Sheldon continued, before spinning the behemoth around and landing one on the guy's jaw that sent him sprawling to the dirty pavement. With a lightning quick move, Sheldon had the shortest of the three lying on the ground the same as the other two.

As Sheldon reached out to make sure Penny was okay, Penny looked down at the three assailants. The tall one sat gripping his leg, but she could see a trickle of blood start to ooze out from under his fingers where Sheldon had stabbed him. The one who had been about to rape her looked dazed from where his skull had collided with the pavement. The short one looked the best out of the three, not having put up any struggle when Sheldon threw him to the ground.

"Are you okay?" asked Sheldon.

"Yeah, thanks to you," she replied in a slightly shaken voice. "A few bruises, I'm sure, but nothing that won't heal."

"Good. Now I believe what we discussed Tuesday night no longer applies, but I'd rather not do it here. Too many uncontrollable variables."

Sheldon held out a clean knife to Penny, which she took with slightly shaking hands. Sheathing his own knife momentarily, he quickly made a makeshift tourniquet to slow the bleeding from where he had stabbed the tallest one. After this, he tied one hand each of the tallest and shortest to the hands of the biggest guy, and made them stand up.

Pulling back out his own knife, Sheldon showed Penny how to keep her knife pressed into the back of the shortest guy without it being visible. He then did the same with the tallest guy on the opposite side, and they marched the three men forwards and out of the alleyway.

Ten minutes later, they led the three assailants up the stairs of their apartment building and into 4A. Sheldon took the biggest and tallest and sat them on the floor against the wall, while moving the shortest to the center of the room. After Sheldon and Penny moved all of the furniture out of the way, Penny plopped down on the couch in her spot to watch.

After Sheldon had dispatched the first two assailants, he walked over to the one remaining, the leader of the group, the one who had tried to rape Penny, the one he'd forced to watch his two comrades being slain.

"Save me!" the last remaining assailant cried out to Penny as soon as Sheldon removed his gag. "This guy's a complete lunatic!"

"After what you tried to do to me?" smirked Penny. "Oh, I think not. Anyway, I have to live with the guy. And trust me, I do not want to have to worry about whether he's going to kill me in the middle of the night."

Once Sheldon had finished, Penny stood up. "I assume you don't need any help cleaning up, so I'm off to bed."

"Goodnight, Penny. See you in the morning."

The following morning, Penny walked into the kitchen in hopes that she was early enough that Sheldon would make enough breakfast for her as well. It was French Toast day, and he made the best French Toast she'd ever eaten. Glancing towards the living room, she saw it was as clean as ever. Turning her attention back towards her tall roommate, she was surprised to find a plate being held out to her.

"Thank you, sweetie," she said, before leaning up and giving him a quick peck on the cheek. She knew he probably didn't approve, something or other about germs, but the ending of their first date hadn't exactly been the most romantic, so she was making up for it now.

Sheldon soon joined her on the couch, and they ate in comfortable silence. When she finished, she turned slightly so that she could look up at Sheldon.

"You know how you asked me if I could ever marry you, and I said I didn't know?"

Sheldon looked over at her slowly and nodded, looking slightly nervous. Penny smiled at him.

"I've changed my mind. After last night, the answer is definitely yes."

A/N: I think this is the end, although I said that after the first chapter, and this is the fourth chapter. But I don't currently have any plans to continue it.