Warning: Serious Sexual here, with the help of my friend. I told her I have been going through a block and she thought of this. And when she wrote some of it, I had to take quite a few things out because it was too erotic. And as you can tell, she's not afraid to let her sexual side in writing out. So I hope it's not too over the top.

The first time Derek saw his stepsister masturbating, it was the most erotic sight he'd ever laid eyes on.

She laid on her bed, oblivious to his presence, her hand sliding inside her bikini bottoms. Her other hand roamed underneath her tank top. Her cheeks were flushed and rubbed against her bare shoulders as she squirmed over the covers.

He'd come home not ten minutes ago from the airport. It was his first official off season since he had gone pro and he was excited for the summer ahead. And he wanted to get a few hours of hanging out with the family before they went about their own business. He was looking forward to a nice welcome home dinner or something. Apparently she'd been so consumed by her task; she hadn't heard him come in the house. When he'd reached the top of the stairs, he saw that her door was ajar. Before he could knock and say hello, he'd caught sight of her through the crack.

He was instantly mesmerized.

At 22 years old, the only time Derek had seen a girl masturbate was in porn. Now he was watching his stepsister, Casey, feverishly finger herself, working her body into a frenzy.

And he was instantly hard.

He wasn't really surprised at his reaction. I mean he was a guy of course, and he had always had a thing for Casey and he thought that she was a combination of beautiful and hot. Well seeing her in the state of arousal she was in, she was hot. Screw the beauty he was used to seeing. He was introduced to sexy with her now.

Besides, Casey was beautiful. Long, brown hair that flowed to the middle of her back, big blue eyes, and a smooth olive complexion. At 21, she had a natural beauty and a body that rivaled any girl Derek had seen in real life. Victoria's Secret models and actresses didn't count, by his standards by any means. But she was normally so prudish. A girl that kept her legs firmly closed. It wasn't just seeing her like this that excited him so much, it was the fact that masturbation was the last thing he had ever expected to find her doing. She always wrinkled her nose at any talk of sex and she had always said that it was disrespectful to women to talk about it before she would leave the room. So, despite her good looks and physique, Derek never really thought of her as a sexual being.

As he watched, her pace quickened and a soft panting escaped her lips. Derek's member bulged against his jeans, and he flirted with playing with himself right there outside her door. Instead, he adjusted his package. No need to squirt jizz on his jeans.

Her panting became more fevered and immediate. Her hips began to rock against her buried hand, and the one under her shirt descended to her waistline, tugging distractedly at the strings that held up her bottoms. It was like she wanted and yet didn't want to take them off. Her tugging had lowered them slightly, revealing the edges of her hips and exposing her smooth tummy. Her free hand quickly untied one side, and then joined the first. She now had both hands working herself.

Her eyes were closed and she was biting her lip, her tiny little moans tickling Derek to a raging hard on. She was the picture of sexy, so sultry and evocative, that Derek wanted nothing more than to join her. But he didn't want to embarrass her or himself. And he was enjoying his peep show far too much.

Her rocking hips began to thrust harder, and her brow furrowed, her face scrunching up in ecstasy. Her head fell back on the bed, her mouth hanging open, frozen in a silent cry of delight. Her back arched up into the air, and she looked almost in pain for instant, before the breath that was caught in her chest escaped in a heaving, trembling moan that sent shivers through Derek's entire body.

Casey's orgasm quivered through her body, her eyes held shut as she settled back down on the bed, her hands still working inside her bottoms, but slower and more gently. She cooed against her shoulders, shivering briefly. He saw her body shake and tremble every time she would hit a sensitive spot. And then she spoke for the first time since Derek had stumbled upon her.

"Oh, Derek..."

His eyes popped wide and now his breath caught in his chest. Had he heard that correctly? Had she really just said his name? Did she know he was there? Of course not, her eyes hadn't even opened yet. There was no way she could have seen him. But she had to. She just said his name. He stood there, almost afraid that she was going to get up, storm over to him in a Casey fit and smack him for being a pig.

"Oh Derek, Derek, Derek..."

She moaned it over and over again, as if putting herself to sleep with it. And then Derek realized, she wasn't saying it to him. She was imagining him. She was fantasizing. She was getting off thinking about him. And god damn was it hot.

And enough was enough for him. He hurried to his room and debated whether or not to take care of his raging hard on now, or just to take a cold shower. He chose a shower. He left his room and as he walked past Casey's room, he saw her still in the same position as she was in when he was being a peeping tom.

Five seconds later he was naked and under the soothing water, jerking off furiously. Derek had never thought about Casey while masturbating before, and now that he was, it was the most intense J.O. of his life. Burned in the backs of his eyelids was the image of Casey's face, biting her lip, eyes fluttering in rapture. He mentally undressed her, imagining what she might look like sprawled out naked, fingering herself, one hand rubbing her clit while the other worked a finger or two inside her pussy. Then, just as he neared climax, she opened her eyes and met his, a deep, wanton gaze that begged him to join her. And he heard those words again escape her soft lips.

"Oh, Derek..."

And that was all she wrote. With a quiet groan that still echoed against the bathroom tile, Derek came in the shower, the warm spray tickling the head of his cock, the image of Casey just as strong as ever. Welcome Home D.

Despite her beauty, he'd never thought of Casey in that way. He wasn't sure why. Even though they weren't related by blood, some part of Derek's mind had decided she was off-limits, but it didn't stop him from thinking she was hot. Now, after seeing her in her room and then jerking off in the shower, Derek honestly couldn't imagine anything or anyone more erotic.

After he dried off, he got dressed. When he came through the doorway of the bathroom and got to his doorway, he was suddenly jumped on from behind.

"Boo!" Casey shouted.

"God Case,"

"I didn't know you were coming home for the summer." She said to him as she got off his back. "Thought you might have decided to spend it with Lauren."

Lauren.

Lauren was his most recent girlfriend whom he thought he should kick to the curb, which he did. He just didn't see anything else happening with her. See, Derek liked to have sex. If sex was a sport, Derek would have gone pro in that instead of hockey. And he was lucky to find someone who enjoyed sex as much as he did. But there is a limit as to how much sex you can take. Sure sex feels great and all and it's a hell of a lot of fun but that was all the two of them did. It was just sex. Before he left for the road, they would have sex, when he got home, they would have sex. Hell, he even tried phone sex but he felt ridiculous doing it. So he ended it.

"Yeah, change of plans."

"Well, I'm glad your home." She said, honestly. "I missed having you bug me at school."

"Oh, if only I didn't get signed." He sighed out.

She rolled her eyes playfully at him.

Over the years, they had set their differences aside and tried that whole friend thing out. And it turned out, it worked great for them. And it seemed it worked great for everyone too.

"Nice winning goal too," she said smirking.

He looked at her surprised.

"I watched some of your games," she insisted.

"Wow."

She shook her head and started walking down the stairs. And just watching her walk away, made him hard all over again.

--

"So, when did you get here?" Derek asked when he stepped out in the back.

His dad and his step mom had the yard redone and had also paid to have a pool put in. At least they didn't have to go over to the Davis' house anymore.

Casey was still in her bikini Derek had seen her masturbate in and a pair of shades, and she was currently floating on a raft.

"Yesterday," she answered.

"How's Landen?"

"Broke up," she said as she floated right in front of Derek's legs that were in the water.

"Why, he couldn't get it up?" He smirked.

She tore off her sunglasses and splashed water at him.

"Shut up," she snapped.

"Was he really bad in bed? I know," he paused, "he was a shriveled up roll of dimes wasn't he?"

"He cheated," she threw at him.

And Derek stopped.

"Sorry,"

Casey sighed and shook her head.

"And not only that, I didn't see it going anywhere." She said, "And what about you and Lauren?"

"Didn't wanna deal with her anymore," he said. "And I didn't wanna be tied down for the summer."

--

After a long evening of asking Derek questions about being pro by his family, and the welcome home dinner he wanted, he headed to bed. His family had decided to go out to the drive in meaning they wouldn't be home till after midnight and he decided to stay home. He was way to tired to do anything at the moment. As he walked to his room, he stopped by Casey's door and pressed his ear against the door. He didn't hear anything so he continued to his room.

He threw himself on his old bed and fell into an erotic sleep.

He was woken up about an hour later by a soft knocking. He opened his door thinking that someone was trying to get him but saw no one. He continued to hear the knocking and looked around the hall. He went into Marti's room to find that she wasn't there meaning that the family hadn't come back from the movies. And then he heard it, soft moans coming from Casey's room. He turned slowly to her door and saw that it was open slightly. And not being able to resist and being horny as ever now, he peeked through the crack.

This time she was completely naked and she wasn't using her fingers. She was using a pink vibrator, working it in and out of her quickly. Her back arched as she tried to open her legs wider. He could tell she was at it for quite some time because her body was covered in a light coat of sweat and her lips were red from the quick movements of her vibrator. Her breasts were firm and perky with extremely hard pierced nipples which shocked him the most. And it turned him on more.

As more soft moans came from her mouth, his hard on became harder. He had to force himself to stop before he started working himself into a climax. He wanted to but he didn't want to. Actually, he wanted to kick open Casey's door and fuck her senseless, hard and rough.

He saw her hips rocking and he heard the knocking again. Her head board was barely knocking on the wall in her room, the wall that connected her and Derek's room. Suddenly, he saw heaven spurt from between her legs and splash on her thighs and he wanted nothing more than to be the one to cause it. He saw her hand moving faster and semi loud moans of 'Derek' were pouring out of her mouth as her back arched. And then, right before his eyes, he saw her hand land on her clit, rubbing furiously making her yell out his name and cum hard.

Her arched back returned to the bad and he watched her body tremble. He couldn't take it anymore. He needed her now. He pushed open the door quietly and he cursed to himself as the door creaked. Casey's eyes shot open and she looked at Derek with his very noticeable hard on. And wordlessly, he walked over to the edge of the bed and grabbed her legs, pulling her body closer to his face.

"Derek,"

He ran his hands up her stomach and to her breasts and she shivered. His tongue darted out and licked her thighs, lapping up her juices that had poured out of only minutes before, tasting her. He moved to her other after a few minutes and started moving to her center. She was completely shaven much to his pleasure, and he licked her lips gently making her whimper. He saw what looked like fresh wetness gush out before he lapped it up. Her legs opened wider for him and he froze. He was completely taken aback at the sight of another piercing. Not being able to contain himself any longer, his mouth latched on to her clit and he began sucking on his roughly. She let out a surprised moan and arched her back.

She had had guys go down on her before but it wasn't like this. She always knew that Derek was very experienced in the sexual department, but she didn't know he was this good. She grabbed a fist full of her blanket when she felt his teeth begin to pull at the metal barbell in her clit. She moaned loudly and felt more wetness gush out of her.

He finally slipped his tongue in to her and started twirling around. He had picked up the talent of twirling his tongue on accident. It was actually just something he picked up and knew that girls liked a guy who knew how to use his tongue.

Her hips started moving against his face more, trying to make him go deeper but he pulled his face away. He climbed over her, circled his tongue around both pierced nipples and moved his way up to her neck. He kissed her neck and moved to her lips and for the first time since they became step siblings, he kissed her. It had been something he had wanted to do for years. He kissed her deeply and she moaned into it.

"God, I want you, Derek." She moaned out making him groan.

"I want you so fucking bad right now." He admitted without thinking.

She kissed him again and flipped them over. She straddled his middle and broke the kiss. She reached into his boxers and gripped his hard on. Her small hand began to pump up and down on him slowly. He groaned and she started moving her hand faster. She then felt pre cum drip and smear on to her hand and she pulled away.

"God, don't stop," he whined.

She giggled and got off him. He watched her hands grip the band of his boxers and give them a nice tug. He helped her remove his boxers by lifting his hips. And not really prepared for her next move, he shuddered when he felt the tip of her tongue trace the head of his member. He groaned. He didn't think that Casey would give him head like she was. Then again, he never pegged Casey for a girl to please herself like he had seen her do for the past day. She was literally full of surprises.

After a few minutes of giving him head, she started moving faster, alternating between her mouth, her hand, and sometimes both.

"Shit, Casey," he groaned out.

And that was her call to stop. She climbed over him, staying up on her knees as he sat up. He saw her wetness still between her legs and her thighs before he kissed her collar bone. He kissed her neck and that spot behind her ear.

"I wanna fuck you right now." He whispered in her ear.

Her response was a moan. She kissed him deeply, got to his knees and lay down with her beneath him with her head slightly off the foot of the bed. He kissed her neck and slid into her quickly and roughly. Derek groaned at how tight she was and Casey moaned out loud and wrapped her legs around his waist. He started thrusting quickly into her making her back arch against him. He rested his head on her shoulder and let out a shuddered breath. He kept a constant rhythm, in and out, in and out, fast and rough. Even her moans matched his thrusts.

She then unfolded one of her legs and he hooked his arm under her knee and pulled it higher making her tighter around him and letting him reach a new spot within her. She cried out his name loudly and returned his thrusts more roughly.

"God, Derek," she moaned out.

He started speeding up making short moans and gasps pour out of Casey's mouth. And it's a rule, no matter what kind of sex a guy has with a girl, oral, regular, you have to tell them that you're going to cum. Well Derek only got out her name before he pulled out. She gripped him quickly and she felt him release against her sensitive skin milking her climax. He entered her again and felt her shake beneath him. Not just diving right into it, Derek decided to take it slow for a little bit so that Casey could come back down because he knew how the female body was after an orgasm. And by the looks of how her body was shaking, it seemed like she had a pretty powerful one.

After about three minutes of going slow, Casey started to meet him with more powerful thrusts. And with this sudden encouragement for him to speed up, he did but only for a minute or two. Casey then somehow pushed him back so that they were back at the head board and she straddled him. She took him in and started riding him quickly. Derek ran his hands over her thighs, up her sides and stopped at her breasts. She moaned a little when he began teasing her with his thumbs. He sat up and took one in his mouth and she bucked harder against him.

She whimpered when he began to pull and tug at her nipple with the metal ring. Casey started speeding up and she let out a long moan. Derek quickly flipped them over and started pounding into her rougher than before. The head board was banging into the wall loudly. It was so loud and seemed like it was so rough, Derek thought he would bust a hole in the wall. Not that it would bother him because it would be easy access to Casey's room because he knew that after this night, he would always crave Casey. He buried his face in the crook of her neck before he groaned.

"God, I'm gonna cum again," he panted out.

He legs that were pressed against his sides, wrapped around his waist tightly, silently telling him that it was okay for him to let go inside her.

He groaned again and moved faster. Suddenly, Casey went stiff and let out a loud moan. He felt her wetness gush out as he continued to pound into her. And with a shuddered groan, he came hard. So hard, he couldn't keep up with his thrusting. They became staggered and slow before he pounded into her once more getting a whimper from Casey.

She shook uncontrollably. Derek cupped the side of her neck and kissed her neck while she shivered, whimpered, and convulsed. Her back arched against him and she held her breath in a pathetic attempt to calm down but failed. She still shook like crazy. Either Casey had never had an orgasm like she did or Derek was a god in bed. He liked to think that he was a god just because that's what he usually got called in bed.

And after what seemed like an eternity, Casey stopped shaking and she sighed.

"God damn," she sighed out.

"You're tellin me."

Derek rested his head on her shoulder and he pulled out. She whimpered and covered herself with her hand making her twitch a little. He smirked while he watched her get under her covers.

"What's wrong? Embarrassed?"

"No, I'm cold."

He then got under as well and sighed.

"Not that I mind, what was that all about?" Casey asked.

"I don't know," he lied.

"Liar," she said sitting up.

"Okay, fine." He said, "I haven't seen you in a year. So when I came home I thought we could do something together but I saw you doing something else. So think of this as a welcome home present."

"A welcome home present,"

"Yeah," he paused, "and I was really horny after seeing you get yourself off."

"You were spying on me earlier today?" She asked shocked.

"Hey, you're the one who can't keep your 'oh Derek's' down." He said smirking.

She rolled her eyes.

"Well then, welcome home to you too." She said before she kissed him.

"Mmm, welcome home," he smirked and kissed her again.

His hands traveled between her legs and lightly touched her lips. She pushed his hand away and looked at him.

"I'm tender." She whined out and he chuckled. "So, why didn't we do that sooner?" Casey asked him.

"I don't know. I didn't think it was an option."

"Well, now it is." She sighed out.

Casey moved closer to Derek and snuggled into his side.

"We still have the whole summer." He smirked.

And that's how it was all summer. And Derek thought he was just tired of sex but the truth was, he was just tired of sex with that Lauren bimbo. And sex with Casey, it was mind blowing every time. And the 'rents never found out. They never found out the reason to why Derek and Casey had become closer than ever and they didn't know that Casey went to every home game for Derek. They also didn't know that after every home game, she would go back to his apartment for a nice orgasmic roll in his bed, or his couch, or in the shower, and maybe his small kitchen.

So here it is. And lets just hope I don't get in trouble for this fiction or anything. I tried to add things in to make it a little less erotic that it was planned out to be. So enjoy pervs!! Oh, wait, I guess I'm a perv too! LOL