A/N. This fic is inspired by a short story called "Heart of Ash" by Jim C. Hines. The story puts ancient Greek nymphs in a modern setting, using the idea that a nymph and their character is defined by their lovers' desires.

Nick stood unnoticed at the door, watching as Greg danced around his lab. The young blonde had started working at CSI two weeks ago, and Nick found himself drawn in by the man. Greg was a nymph; it wasn't a secret, and Nick had seen him flitting between personalities on a whim for over a week. His hair changed from blonde to black and fire red. It had been long and short; he'd even had a mullet at one point. Nick preferred him like this; when he was alone. When he was himself. Nick thought he was beautiful like this. He looked free; the slight desperation that showed when there was too much lust dancing around him was completely gone. Nick had tried to avoid being alone with Greg. The pull he felt towards the man scared him a little. Today there was nothing he could do. He was solo on a case, and he hadn't met anyone already on their way to the lab. With a sigh, and reluctant to make Greg change, he knocked on the glass door. Greg stopped dancing, his eyes immediately falling on Nick standing nervously in the doorway. Greg turned off the music.

"Hey," Nick spoke quietly. "You busy?" Greg smiled widely.

"I've always got time for you." The suggestive tone Greg used made Nick's heart flutter, and he tried to stay focused.

"I've got some DNA that needs to be run," Nick put the evidence on Greg's workstation, stepping back a little. "There's a few fingerprints, and some chemical trace too." Greg opened the evidence bag; his excited attention on the work he had to do.
"Page me when you've got something?" Nick asked. The wide smile Greg turned on him stopped Nick in his tracks.

"No problem." Nick nodded slowly, coming back to himself as he stepped out of the lab. The music started back up and Nick smiled as he wandered down the hall. Suddenly, a thought crossed his mind. He'd been so busy trying to control himself, he hadn't realised those eyes were the same sparkling blue. His hair had remained short and dirty blonde. Nick had been with Greg for ten minutes, and not a single aspect of the nymph had changed. With a soft smile, Nick continued down the hall. He was glad Greg didn't change around him; Nick thought he was perfect the way he was.

Greg laid his head on the desk with a sigh. He'd been run off his feet all day; too much evidence and not enough time. And to add to the stress, all the people milling in and out of the lab had his body in overdrive. Techs lingered longer than they needed to. Day shift CSIs came in smelling of sex. Greg had even sensed a pregnancy. He'd told the woman in question, and then lost twenty minutes to excited squealing and jumping around. What seemed to bother him more than anything though, was that Nick hadn't come back for his results. Greg had paged him, but Nick had sent an intern to pick it up for him. The intern had mumbled something about a break in the case; his cheeks stained red from the sexual tension. Greg didn't flirt with him. The lust rose, like it always did, but Greg didn't feel like playing with anyone right now. Ever since Nick and his soft smile had left; Greg didn't feel right. It was almost as if something was missing.

So, when a knock on the glass turned out to be Nick, Greg's tired eyes lit up.

"Hey." The voice was nervous, but the smile was genuine. "You wanna go grab some breakfast?" Greg nodded with a bright smile of his own. With a quick check that everything was where it needed to be, Greg slipped off his lab coat and followed Nick out of the labs.

Nick drove them to a small diner on the edge of the strip. It was quiet; only two customers besides them. Greg followed Nick to a small booth at the back; the furthest distance away from the only awake patron, who was currently eyeing Greg hungrily. It made Greg blush that Nick had noticed this man without even looking, and instinctively put himself between the two.

Greg watched Nick curiously as the older man studied the menu. The feeling Greg got around him was strange; familiar but entirely new. The desire was there, bubbling at the surface, but it wasn't as frantic as it had been with everyone else lately. The lust was calming, in a way; like it had always been there. Add that to the fact that Greg didn't change around Nick, and the nymph was confused.

The form he was in now was not the one he had left San Francisco with. Greg had woken up the morning he was due to start work at CSI looking exactly like this, and he didn't know why. He felt lighter around Nick; more carefree. Like he had when he was a wild nymph; before he'd been domesticated around 100 years ago. He was too urbanized now; no way of going back, and Greg didn't miss the way he was. But he did miss the lightness in his heart sometimes. His last lover had been a very serious man, and Greg hadn't had much laughter in his life. He'd loved William; he didn't doubt it, but the life of a high court judge was a stressful one, and Greg's personality had molded itself around that severity. But here, sitting in a diner just outside the bad part of Vegas, Greg felt like he could laugh for no reason, and he was beginning to think Nick was a big part of that. He just had to figure out how.

A waitress stopped at their table, and Nick surprised them both by ordering for Greg. The waitress simply smiled, like it happened a lot, and left them in peace.

"Sorry," Nick mumbled once she'd left. "I shouldn't have done that."

"It's ok," Greg's smile was a little brighter than the situation warranted. "You ordered just what I wanted." That wasn't entirely true. Greg wasn't very hungry; but the urge to please Nick, to get that sad look off his face had taken over. Greg was beginning to feel that familiar sensation in the pit of his stomach. His eyes locked with Nick's, and Greg had to subtly grab the table in front of him to reign in his instincts. Every nerve in the nymph's body was screaming to open himself up, to pull Nick in like he knew he could so easily. Greg forced himself not to listen, smiling internally as a thought hit him. Many were disturbed by the thought of taking a nymph as a lover. They saw it as a kind of slavery; believed since the nymph couldn't control it, it couldn't be real. And yet here Greg was, using all his self restraint not to control Nick's behaviour. I would come as easily as breathing, and people called him the slave? Greg looked up to see Nick eyeing him curiously. Perhaps he hadn't been as effective in hiding his feelings as he thought. With a reassuring smile to Nick, Greg put his hands back in his lap.

"Everything ok?" Nick asked; voice laced with concern and confusion. Greg opened his mouth to lie, finding himself unable. With a soft smile, Greg got to his feet.

"I'll be right back," Greg's voice was almost a whisper, as he swept past Nick towards the restroom. Nick sat for a moment, unsure of what to do with himself. Greg was little more than ten feet away, and Nick was already feeling the loss. A few minutes passed before Nick was unable to stop himself following Greg.

Nick found Greg at the wash basin; staring at himself in the mirror. Nick stood behind him silently; watching as the nymph's reflection shimmered. Eyes changed from blue to bright gold and back. It took a moment, but Greg noticed Nick in the mirror. Nick saw Greg's hands tighten on the basin, before the blonde was turned to look at the CSI. Nick's eyes widened as Greg stepped closer; eyes flashing.

"Give me permission," Greg spoke softly, but Nick heard him. He didn't understand, and Greg's proximity wasn't helping his brain function. Placing his hands on Nick's chest, Greg stared into his eyes.
"I can't hold it much longer, Nicky, please." Nick was taken aback by the desperation he heard. "I don't want to force you. Please." Suddenly it dawned on Nick what Greg was talking about. Nymphs had a power; everyone knew it. Nick had almost forgotten Greg was anything but human. Licking his lips, Nick found his throat suddenly dry. Slowly, he nodded his consent and the smile Greg gave him was blinding. Leaning in, Greg let his lips brush softly over Nick's, and the CSI was immediately lost. Desire swirled around him and through him; the world falling away and leaving nothing but him and Greg. His mind barely came back to him when Greg moved away.

"Let's go home," Nick mumbled hazily. Greg smiled widely and nodded; taking Nick's hand for both stability and comfort. Nick squeezed the hand in his as they walked out together.

The End.