Author's Notes: Wow, I was on a roll. I didn't expect to finish this part until later today. It's a whopping 3:39am here, so you can imagine my annoyance (I have to work in the morning). This is the end of my first Grey's story, and I must say I am very pleased at the way it turned out. I'm also pleased that it didn't go longer than three parts, as it usually does when I plan little ficlets. Anyway, as I've said before, I will be writing a sequel and it will be full-fic. We'll get to see the repercussions Izzie's so worried about. Should be fun. :) I hope you've enjoyed reading this as much as I have writing it. I had to change the rating due to the explicit content in this part. It's not graphic, but better safe than sorry.

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Part III: Derek & Izzie

Derek and Izzie didn't se each other for the rest of the day. He had four surgeries (all of which went swimmingly well), while Izzie spent most of her day in the clinic. Both avoided their respective former partners as well as each other. But neither stopped thinking about last night, both often reveling in the details whenever they had a moment of peace.

After a grueling shift, Izzie made her way to the on-call room. A few hours of sleep would do her some good right about now. She was pulling a double shift tonight, and couldn't leave with her roommates. It was just as well. She couldn't face Meredith right now, and she didn't want Alex to pick up on her tension. The man was like a school-girl when it came to gossip.

She walked inside the room, finding her way to the bottom bunk in the pitch dark. Plopping down she landed on someone with a loud oomph.

"Oh, God, I'm sorry!" she exclaimed and shot off the bed. She turned on the light and the person blinked a few times, trying to adjust their eyes. Izzie did the same and a knowing smile curled the corners of her mouth when she saw Derek looking back at her.

"You know," He grinned slowly. "There are other ways of waking me up." He let the cover fall off his bare chest, knowing Izzie's gaze would follow. When it did, he laughed. "I can show you a few if you'd like."

Izzie rolled her eyes, but unconsciously flicked her tongue across her lips. "Somehow, I knew it would be you."

"Because we're so connected?" Derek playfully asked, vaguely reminding her that they'd been remembering the same things all day.

"No, because I'm just that unlucky." She tossed him a smug smile.

"Ouch. And here I thought we were becoming fine friends."

Izzie crossed her arms over her chest and looked at Derek with disdain she did not feel. "I think after last night, we both know friendship is not possible."

"Why not? Friends have sex."

"Yeah," Izzie responded. "Friends with benefits. You and I shouldn't be those kind of friends."

"Well, what kind of friends should we be?" he asked playfully.

"The kind who says hi, bye, and then go their separate ways. The kind of friends who should feel guilty about betraying their other friend and not make googly eyes at each other in the hallway of the hospital they work in."

Derek rose from the bed and walked toward her. Izzie chided herself for enjoying the way his scrub bottoms hung loosely on his hips. She enjoyed the sight of his chest hair, knowing how soft it felt to the touch. He stopped just in front of her, a charming smile curving his mouth. He smelled intoxicating to her, just as she did to him. He couldn't wait to unpin that hair and have it fanning out over the pillow the way it did last night.

He placed a big hand on her hip. "First," he began softly. "I don't make googly eyes." He advanced upon her, his other hand bracing against the door next to her face. His gaze locked with hers, holding her there with him. "Second, if you want to be the kind of friends who go their separate ways, perhaps you should leave."

Izzie smiled at him, a warm smile that seemed to radiate from her entire being. They both knew she had a hard time walking away.

Izzie's hands fisted in the pillow behind her head. Her eyes fell blissfully closed and her mouth parted with a soft whimper. The beads of sweat prickling along her skin did nothing to cool her down. Her body was too… she couldn't find the proper word. Derek had rendered her speechless as well as turned her brain to mush.

Derek hovered above Izzie. His naked body covering hers possessively. He grabbed her hands and pinned them above her head. Looking down he marveled at her. Marveled at her uncanny beauty, how her body felt so perfect, how responsive she was to the things he did to her. He marveled how his own resilience seemed heightened in respect to hers. She made him want to go further. To push deeper, bringing her closer to the release she desired. Yearning for the release of his own.

Izzie opened her eyes to see Derek staring down at her. Somewhere in the back of her mind, she half expected him to be looking through her. To be imagining Meredith underneath him instead of her, but she was pleasantly surprised to see he wasn't thinking of Meredith at all (or at least it seemed that way). He seemed very much in the moment… with her.

"Oh, God, Izzie," he moaned, and she was certain he was with her. He pushed hard against her, aching to go deeper, and Izzie wrapped her long legs around him to allow him.

"Let me touch you," she whispered breathlessly. Her eyes wide with joy and pleasure. "Please."

Derek shook his head. "No. If you do, I'm afraid I'll come undone."

Izzie laughed, a short soft laugh that touched something deep in his heart. "I have that kind of effect on you?"

"Oh, yes," Derek admitted without any hint of embarrassment.

"Fine," she responded, and leaned up and captured his lips with a kiss.

Derek moaned in response and it wasn't long before either of them came undone. Izzie's orgasm coiled in the heat of her belly. Winding up tightly like a spring, tighter and tighter until Derek pushed her over the edge. Waves of pleasurable heat trickled through her, causing her to writhe in spastic movements. Derek's own release cut through him like a knife; he cried out as wave after wave crashed over him until he fell against her.

They stayed that way for a long moment. Both allowing their bodies to come down from their respective highs, and for their breathing patterns to return to normal. When they did, Derek rolled off of her onto his side, and reached out to grab her and hold her close.

Izzie hadn't felt a closeness like this in a very long time. She thought (foolishly) that she could share this kind of closeness with George. Finding it with Derek was shocking. Derek felt her tense in his arms and angled his head to get a better look at her. The moonlight shone brightly on her pale skin, casting its silvery glow on her long blonde hair cascading down her back, flowing around her making her look like a goddess.

"Iz," he called her softly. She looked up into his waiting gaze. "It wasn't wrong," he told her, knowing the words would bring her little comfort, but also knowing she needed to hear them. When she lowered her eyes, he kissed her forehead gently.

They lay together, two unlikely lovers, listening to each other's heartbeats and the quiet that surrounded them. Despite their feelings of guilt, their contentment was palpable. Izzie was the first to break the silence.

"I haven't felt this close to anyone in a long time," she admitted to him softly. "With George it was forbidden and when it wasn't… it just wasn't the same." She raised up on her side to look into his face. His expression was unreadable. "Did I just freak you out?" she asked, worried that she'd crossed some invisible barrier.

Derek chuckled softly. "No," he answered. "Not at all. I like that you're so open about what you feel." He brushed a hand over her face lightly. Izzie folded her arms across his stomach and leaned on them. "Meredith isn't very good at opening up."

"That's a big thing for you, huh?" she asked, intrigued to know more about him. "Communication. Honesty."

"Yes," he answered. "How can you be in a relationship if you can't share every part of yourself? Or at least a relationship you expect to last a while."

Izzie shrugged her shoulders. "Most people don't like sharing themselves. They think it will make them vulnerable. They close themselves off in the hopes that they won't get hurt."

"But that only screws them up more," Derek said. He ran a hand through her hair. Enjoying the warmth of her skin, and even the way she leaned against him. "What about you and Denny? Were you this close?"

Izzie sighed heavily, her breath tickling the hairs on his stomach. "We were, but that was cut short. I think I'm always searching for that kind of closeness again. I think… I know that's why I developed feelings for George. He'd always been there for me. He…" her voice trailed off sadly. Her gaze drifted away from Derek's eyes briefly before flickering back again. "We can never tell anyone about tonight, you know that right? The repercussions of this would destroy not only Meredith, but our friendships with a lot of people."

"Izzie," Derek hated that she'd suddenly turned sullen and serious, though he understood completely. "I…" He didn't know what to say. Didn't think there were words to truly express what she'd given him this evening, what she'd awakened. However, she was right. Their affair (though neither were attached to anyone else) had the potential to hurt a lot of people. The thought of her losing all her friends when she'd lost so much already was one he just couldn't bear. "I won't tell anybody, and I won't pursue this if that's what you want."

"That's what I want," Izzie replied smoothly. She was mentally kicking herself for not walking away from him when she had the chance. Kicking herself for being weak. She pushed herself off him and rose from the bed. Standing naked before him in the moonlight, Derek was certain he'd never seen a more beautiful creature. He cursed himself for not seeing it before. For not realizing what was right in front of his face all along. He had no doubt now that he and Izzie could have been something great. They could have been what he'd wished he and Meredith could have been. It was a hard pill to swallow, knowing it was too late now. Their fates had already been laid out before them. Izzie looked over her shoulder at him as she started to dress. "Are you okay?" she asked.

"Yeah," Derek replied, finally sensing the darkness of the room. Finally realizing what this secret would cost him… what it would cost them both.

"So, what's it going to be, Isobel Stevens?" Derek asked, pressing his body further against hers. "It's in your hands to decide what kind of relationship we have."

She didn't look as taken with his charms and he'd like. Her warm smile had faded and in fact, she now looked frightened. "Derek, you said you wouldn't pursue this if that's what I wanted."

Derek nodded slowly. "I did say that." He smiled charismatically. "And I'm not. I'm letting you decide."

Izzie then silently wondered how it was possible to want to kiss someone and deck them at the same time.

She stared at Derek and all those feelings she experienced throughout the day came rushing back. The closeness, the joy, the reckless adrenaline… She hadn't felt so alive in ages. She hadn't connected with anyone that way in such a long time as well. Could she really give that up? Did she really want to?

Reaching behind her, she locked the door to the on-call room. To hell with being self-less. She deserved some happiness, too… didn't she? She couldn't help but wonder if her happiness would be worth the loss of a friendship.

Pulling him close, Izzie fused her lips to his in a hot-blooded kiss that sent them both reeling. Derek backed them up in to the room, fumbling with the drawstring of Izzie's scrub bottoms along the way. They dropped onto the bed in a fit of giggles, Derek shooting off the bed in a dash to turn off the light and plunge the room into darkness.

Izzie's breath caught when he found her again.

What's done in the dark is a secret. A forbidden language written across time with the whispers of two lovers. It's a kiss against lips, a flick of the tongue across skin, a passionate embrace. It's freeing and exhilarating and special. It's dangerous and illicit and mischievous. It thrives in the dark...never caring to see the light.