Song- Mad Sounds by the Arctic Monkeys

Three days had passed since Derek slept with the student teacher in the yoga class he was supposed to be taking with his girlfriend. He felt guilty and miserable.

"How many times are you going to wash those sheets?" Mark asked as he watched Derek for what seemed like the hundredth time in the past few days load the same sheets into their washing machine.

Derek ignored him and proceeded to put another wash on.

"Derek" Mark shouted

Derek turned and looked at his friend, a look of despair on his face

"Addison doesn't have to find out" Mark told him

"She's going to find out because I'm telling her when she gets in tonight."

"Don't do that" Mark advised him

"Mark, I cheated on her. I had sex with someone who wasn't my girlfriend who I had just met. I have to tell her. I have to get tested. I don't have time to argue with you."

"Just talk to Meredith find out if she's clean."

"I don't want to talk to Meredith, I don't even want to look at Meredith." Derek told him bringing his hand over his face.

"I really fucked this up."

"Maybe it's for the best" Mark told him.

Derek's eyes blazed

"No really, maybe it's for the best. You and Addie have been together for two years, things get stale eventually and I live with you, I know your sex life is almost non-existent."

Derek left the room slamming the door behind him.

Once in his bedroom Derek layed on the bed he last spent with Meredith, not his girlfriend. His mind drifted to their night together. He felt his lower half responding just at the thought. It had been so good. So unlike his past sexual experiences. Meredith knew what she was doing, he assumed it was because of the fact that she was with an older, much older man. If he was being honest, he wanted to experience her again and again. He had never been so sexually attracted to another individual. He loved her body. It was so toned so sculpted. He loved the feeling of her breasts in his hands and he felt a jealous twinge at the thought of Meredith doing those same things with Professor Hamlock that she did with him. He replayed being in the taxi with Meredith of his lap, his face in her chest, his mouth sucking her boobs while she moaned in pleasure. He imagined Meredith sitting on Professor Hamlock's lap, him licking and sucking all over her breasts while she moaned and played with his gray hair. He felt sick. He felt possessive, he felt like he wanted her all to himself. He wanted her on him only. He wanted her body consistently on his. He wanted his hands all over her exploring, he wanted his mouth all over her plump lips. The mere thought of Meredith seeing Professor Hamlock the day after they had been together infuriated him. The only part that excited him was Hamlock seeing the bruises on her neck and her breasts that he left there. He wanted Hamlock to know that Meredith had been with him.

He quickly pushed the thoughts out of his head. He had no idea what was going on with him. It wasn't like him to cheat on his girlfriend much less fantasize about other girls. He wasn't like Mark. He was a good guy, the kind of guy his mom would be proud of, the kind of guy that makes a promise to a girl and means it. Addison was coming home and he had to tell her the truth.

He heard a knock on the door and Mark came into the room.

"Hear me out okay?" Mark asked taking a seat in the chair located in Derek's room

"Okay"

"You and Addison have been together two years, if you want to be with her, just drop the class and don't tell her. You will never see that girl again and you can go back to how things are with Addison. You two spent almost the entire summer a part, you miss her and Meredith was just a one time thing. She was an accident that was the result of you missing your girlfriend."

Derek was silent.

"Drop the class man. You won't see the girl again and Addison doesn't have to know. If you tell her, she will leave you."

Derek nodded "I don't know what happened, in a week I have turned into a completely different person. I would have never done this to Addison."

Mark was silent.

"What happened Mark?" Derek asked

"Lust." Mark said "And alcohol."

Derek nodded.

"So?"

"So I guess I'll drop the class and pretend it never happened." Derek replied

"Good" Mark said and stood up to leave.

Derek checked his watch, Addison should be back anytime.

An hour later Addison was home. He thought he would be more excited to see her but blamed it on the guilt he felt. His mind was elsewhere, it was on the blonde he met in class, the blonde who was both enchanting and bewitching, the blonde who he desperately wanted to see again.

"Derek, are you listening?" Addison asked

"Yeah, sorry" Derek responded as he came back into reality.

"I got you a little something" Addison told him

"Oh yeah?" he asked

She lifted her top off and then started pulling her pants off until she was dressed in tiny red lingerie.

"What do you think?" she asked

"Wow, um, thanks" he said as she sat on his lap and kissed his mouth with hers.

"Touch me" she purred against his lips. He grabbed her breast into his hand and his mouth immediately went to the other one sucking hard as he pulled off her bra. He couldn't help but think Meredith's breasts were bigger. She moaned and he compared it to Meredith's sexy moan. He entered her and compared everything to the way it felt with Meredith.

"Can we do this without a condom?" he asked

"Why would we? You always wear a condom?" Addison asked confused

"I just thought…nevermind, I'll go get one" Derek said pushing Addison off of him.

When he got back he saw Addison sitting and waiting for him and he immediately wished she was Meredith.

"Lets do this" he mumbled.

"If you don't want to, we don't have to Derek, I just figured you would like your surprise."

"I did like it Addie, I'm just not feeling well."

"Oh."

"Are you okay? What are your symptoms?" she asked

"I'm fine just a stomach ache" he told her

"Well if it's just a stomach ache then put the condom on and come back inside" she purred.

His mind flashed to having sex with Meredith and he instantly got hard. He kept his mind on Meredith the whole time and was able to finish. When they were done Addison snuggled close to him

"That might have just been the best sex we ever had." she whispered.

He felt warm.

Meredith was lying in bed with Dean, for the first time she noticed the deep wrinkles around his eyes. She moved her fingers up to touch them and he smiled. His fingers were lingering on her ass and he went between stroking that to her breasts.

"I know we never said we were exclusive baby, but it's a bit of an insult to bring another man's bruises home to me" he said with a smile.

She smirked "Are you jealous?" she asked.

"A little" he admitted.

"I want to be the only one sucking here" he said as he moved a large part of her breast into his mouth and "and here" he said as he moved his mouth to the other side.

She groaned.

He stopped what he was doing and kissed her and she quickly kissed back. In an instant she was on top of him feeling his erection when suddenly they heard the door to his house opening.

"Shit" Meredith mumbled

"It's fine, it's just Lauren. Let me go take care of it" he told her and got up to put his pants on.

"It's just your wife" Meredith blurted

"Baby, calm down" he told her and kissed her forehead before making his way out of the bedroom.

She heard some screaming in the halls and quickly got dressed. She made the bed back as quick as possible and climbed out the window that was already open.

When Lauren made it to the bedroom, all traces of Meredith were gone

"See, I told you nothing is going on" Dean stated.

Lauren looked bewildered.

Outside Meredith called Christina

"Hey, I need you to come pick me up" Meredith told Christina urgently

"I can't, I have class. You need to call someone else."

"I hate you" Meredith responded

"Byeeeee" Christina said before hanging up the phone.

Eventually Meredith got Lexi to come pick her up.

"So I'm not going to ask questions"Lexi stated while she drove Meredith back to her apartment

"Except I am. Meredith what were you doing out here?" Lexi asked

"Don't worry about it Lexi." Meredith stated

Lexi sighed and kept her hands on the wheel

"You know, this was a thirty minute drive."

"Want me to give you gas money?" Meredith asked

"That's not what I'm saying. I'm your sister Mer"

"My half sister" Meredith responded.

"You don't have to like me, a lot of the time I don't like you, but I am your sister and I want to be your friend. I didn't have to drive thirty minutes to come pick you up. I skipped class because you were in trouble and I wanted to help you out, so you can sit here and act like you have a chip on your shoulder and I can disappear and not talk to you but I'm here and I'm trying." Lexi stated exasperated.

Meredith was silent for the rest of the drive.

Lexi pulled up at her apartment.

Meredith hesitated to get out

"Well, aren't you going to leave?" Lexi asked.

Meredith sighed "I'm dating a married man. Don't tell anyone." Meredith told her

"I won't I promise" Lexi told her with wide eyes

"Okay, see you later?" Meredith asked

"Uh yeah, bye Meredith" Lexi stated.

"Progress" Lexi muttered when Meredith was back in her apartment.

Once inside her apartment Meredith broke down into sobs. This wasn't who she wanted to be anymore. She felt badly about what happened with Derek. He had a girlfriend. She was doing this to yet another innocent woman. Sleeping with their significant other just because she wanted to be with someone who wasn't emotionally available. If she was honest she liked Derek, he was cute and charming and young, and he called her on her shit and he gave her a really good time, she just wasn't sure she wanted to be a good time girl anymore.

A few days later when she realized he dropped her class, she was disappointed but also not surprised.

At the end of the class Dean embraced her "You seemed bummed out today" he stated

"I'm fine" she told him.

"I have something that will cheer you up" he told her as his hands moved up and down her back

She looked up at him expectantly "A hotel room for the two of us tonight" he replied

She faked a smile. This was the first time in two years that she didn't want him.