A/N: Thanks soo much for the reviews! And keep them coming;)! By the way, this chapter is a Dasey!

Enjoy!

Warning: probably rated M…

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By then he was right in front of her, she could feel his hot breath and his chest breathing at a steady pace. Derek slowly raised his right hand and cupped Casey's cheek.

A warm feeling was starting to rise in Casey.

'Oh god…Could this be it..'

Slowly leaning in, he placed his lips on Casey's.

'Oh my god! Casey you have to pull away!…But it feels amazing…Casey its fucken wrong he's your step brother! I know…but I just can't…"

Seeing that she hadn't pushed him off yet, he moved his talented tongue along Casey lower lip, begging for entrance into her mouth. After a couple of seconds she finally let him in. They both explored each other's mouths.

Casey's hands made there way to wrap around Derek's neck and started playing with the ends of his soft reddish brownish hair. Derek wrapped his arms around Casey's waist.

'Wow, he's such a great kisser!'

Derek finally backed away from her lips for air, they both looked into each other's eyes. Their eyes both clearly stated the way each other felt about the other.

Derek was starting to let go of Casey and leave thinking what he was doing was wrong and that maybe Casey didn't like him as much as he loved her. Her eyes held a pleading, confused look in them.

But to his surprise, Casey still kept her hands wrapped around his neck and crashed her lips against his. She kissed him deeply letting him know how she truly felt for him. Derek did the same and wrapped his arms back around her.

He started guiding her towards the couch. Casey fell on the couch and Derek crawled on top of her. Derek took off his t-shirt and threw it on the floor. Casey slowly ran a finger down his chest and down his hard built stomach. She then let her arms wrap around him.

Derek slowly started kissing along her jaw line and then down her neck. He let his hands slip under her tank top and rest on either sides of her stomach. Once he was right above her breast he looked up at her with a pleading look in his eyes. Nodding, Casey gave him the signal that he was allowed to take off her tank top. He slowly lifted her tank top above her head and threw it on the floor.

He started kissing down between her breast and down her stomach.

"Derek…" Casey moaned.

"Mmmm…" Derek mumbled between kisses.

Once he reached the top part of her skirt he looked at her. She gave him the nod to say he could take off her skirt. He slowly unbuttoned her denim skirt and slid them down her legs. Derek started kissing up her leg.

Casey moved her hands around the top part of Derek's jeans, she started tugging on them, signaling that she wanted them off. Derek smirked and let her unbutton his jeans. He slid them off and tossed them on the floor.

Casey let out a chuckled noticing his boxers were covered with Tweety bird.

"What he's cool" Derek said innocently.

Derek kissed Casey's stomach and started kissing his way up. When he reached between her breasts, he unclasped her bra. He slid them down her arms and tossed them to the ground.

Casey rested her hands on Derek's head and let her fingers play with his soft hair.

Derek kissed back down her stomach and slowly slid her underwear down her legs, and started kissing between her legs.

"Derek…" Casey moaned.

She moved her hands to the rim of his boxers.

"Uh….Case, are you sure…" Derek asked unsurely, he was pretty sure Casey was still a virgin. She had dated his best friend Sam a little while back. Nobody really knew the reason why they broke up.

Casey nodded.

Derek hesitated, but before he could say anything she had already slid his boxers down his legs.

Casey started kissing down his neck and he completely melted.

He slowly slid himself inside of her. She moaned in pleasure. And so did he. He never imagined himself making love to Casey, his own step sister Casey.

He slowly slid himself in and out of her. When they finally finished he collapsed on top of her(A/N: Not crushing her of course lol). He moved over so she could rest on his shoulder. Casey placed he head on his chest and started tracing shapes all over his body with her finger. Derek wrapped his arm around her shoulder. They soon both fell asleep.

Drrrrring!

At the sound of the telephone both Derek and Casey sat up quickly. Casey quickly reached for her clothes and put them on and started straitening out her messy hair.

Derek got up and quickly put on his boxers and jeans and ran to get the phone before the ringing stopped.

"Hello….Oh hey dad" Derek said glancing over at Casey. "yeah…oh…ok…yeah we're fine…yeah alright send them over…ok bye" With that he put the phone back down.

Casey looked at Derek confusingly, she didn't feel like saying anything after what just happened, she hoped he could figure out what she was trying to ask.

"Uh looks like we're gonna have company. Ed and Lizzie are on there way home, their school lost power 'cause the fixing guy accidentally broke a wire and yeah blah blah blah" Derek said sitting on the arm of the chair.

"Oh.." Casey said barely moving her lips, she could barely look at him either, she kept her eyes staring to the ground.

Derek slid down from the arm down next to Casey.

"So…What just happened" he said looking at her.

"I'm not sure…" Casey said unsurely.

"Was it…ok?" Derek asked. He didn't exactly want the question to come out, especially the way it did.

"Uh, I don't know Derek! We're siblings! We just had sex! DO THE FUCKEN MATH, DOES THAT SEEM FUCKEN OK TO YOU!" Casey stood up and yelled to his face.

"Ok Casey calm yourself, it wasn't that bad, we're not blood related so its not necessarily not ok…Besides…You can't seriously tell me you didn't like it" Derek said, standing up in front of her to face her evenly and lifting an eyebrow.

Casey stood there a moment in shock.

'I did like it Derek…'

"I liked it Case.." Derek said in shock of his own words.

"Well obviously you liked it! You like every sex you have with every girl you have it with!" Casey screamed.

"I didn't mean it like that!" Derek yelled, which shocked Casey, he had never yelled like that at her.

Derek calmed himself and stared at the floor. He started walking away. All Casey could do was stare at him walking away and going up the stairs.

'If he didn't mean it like that…than…what did he mean?'

Casey felt tears building up in her eyes, she didn't want the kids to see her like this so she quickly ran upstairs into her room. She locked the door and laid down on her bed. She grabbed a pillow and hugged it tightly, she wanted to think it all out.

'He said he liked it…he liked it…with me'

Casey's head shot up in realization.

'Does he like me?'