Disclaimer: I don't own them, and they'd probably be very unhappy with what I am doing with them.

Rating is for some randy smut. And there is a bit of GSR angst.

Reviews: I always like reviews, as long as they aren't made with flame throwers.

A/N: This is my first fan fic in the CSI universe. I usually write Law & Order SVU fiction (E/O pairing), but I have a special place in my heart for GSR. And Nick? Well, does he really need an explanation?

For three in the morning, the building was surprisingly quiet. The soles of his shoes thudded softly across the worn tiles of the empty corridor, the rhythmic sound a desired distraction from his current thoughts.

Grissom had just come from another heated argument with Ecklie. One of their open cases had become the current media darling, and in doing so, once again placed Grissom and his ever-suffering team under the partial watch of the Assistant Lab Director. Any error, anything done outside the scope of regulations, no matter how insignificant, would give Ecklie more fuel to his argument to split, as he so eloquently put it, Grissom's band of misfits.

He paused in the deserted hallway, rubbing the bridge of his nose with a sigh. Thankfully Catherine had left an hour ago with Warrick to investigate a DB. Even though he considered her his closest friend, and she had undoubtedly helped him on matters both professional and private over the years, he couldn't fathom discussing this case and its possible repercussions with her right now. His head was already starting to throb, the beginnings of a migraine, and all he wanted was some strong coffee and solitude so he could read through the latest National Forensics Journal in peace.

Grissom resumed the walk towards his office, when a muted giggle stopped him, the girlish sound causing his stomach to clench in a rather sudden, odd mixture of emotion. He turned around, staring down the empty corridor. In the dim light, he could just make out the slightly ajar state of the last lab door on the right. Hearing the hushed sound of voices, he strode silently back down the hall, his curiosity piqued.

He knew the sound had come from Sara. Even underwater, he would recognize the familiar lilt of her voice. Hearing her laugh was something he coveted; it was an action she seldom engaged in anymore, and less so for him. The fact that someone else had coaxed that delighted sound from her caused an unwanted pang of jealous in his chest.

Grissom absently wondered who was with her. For a moment he imagined Sanders; it was painfully obvious the young man had a crush on his Sara, and he had a knack for causing the occasional, unbidden laughter from her. He moved closer, his hand on the cool steel of the door, bringing the scene into view even as the voices confirmed the identity of the lab's occupants.

"Nick…," Sara pleaded in a mocking tone, her voice soft. "You're distracting me."

"Mmm, I think that's the point, Sar," Nick answered her, his voice muffled by her hair.

Grissom stood in the dark doorway, his body suddenly rigid as he took them in. The lab was almost completely dark, save the large illuminated desk in front of Nick and Sara. Grissom vaguely recognized the tattered remnants of Caspiano's bloodstained parachute on the table light, remembering the task he had sent them on two hours ago. They needed to reconstruct this valuable piece of evidence in order to decipher any meaning to the bloodstains left behind.

Sara stood in front of the table, her gloved hands paused on one rather large piece of yellow fabric. Nick was behind her, his face buried in her thick, dark hair, his bare hand tracing Sara's jean-clad hip with a familiarity that caused Grissom's chest to achingly constrict. Of course, this shouldn't have been such a surprise. He had rejected all of her advances over the years, convinced that she was too young for him. A relationship between them wouldn't work. He had saved them both the pain.

But she was a young, healthy, sexual woman. And Nick, well, Nick was tall, handsome, and had no problem attracting the opposite gender. Though not on the same level intellectually with Sara, he could hold his own well enough regarding forensics, and unlike most other men, could actually relate to Sara regarding the job.

So it shouldn't be so much of a surprise to find them together, but it didn't mean the actual revelation didn't stab painfully at his heart.

Sara laughed again, this time lower, almost seductively. Grissom watched in the half-light as Nick pulled back her hair from the left side of her throat, softly kissing the exposed flesh. Sara dropped the piece of fabric, her head rolling back against his shoulder.

She was moaning, and Grissom felt torn. He needed to leave or interrupt them. It would be embarrassing, but as their supervisor, he should reprimand them. Instead, he stood there quietly in the dark doorway, watching as Nick's hands slid down Sara's bare arms, tugging off the latex gloves.

"Just a moment, Sar," Nick whispered, his husky voice nearly inaudible. "Take a break, sweetheart."

The term of endearment made him bristle. Unwillingly, Grissom wondered how long the younger man had been on such a level with her to call her by anything other than her given name or that nickname he had for her. Unwanted visuals of their coupling came into his head, and he closed his eyes, shuddering at the thought of Sara naked, under him instead of Nick.

She gasped, then giggled again, the sound causing his eyes to open. Nick had sat down in a nearby chair, pulling her with him so Sara was on his lap, her legs on either side of his. She was arching her back, her breasts straining against the thin fabric of her white t-shirt, her arms raised and behind her, in Nick's hair.

Nick was kissing her fully on the mouth now, one hand firm on her hip, the other tracing lazy circles against the waistband of her jeans. Grissom watched as Sara rocked slowly in Nick's lap, knowing without seeing that she was rubbing herself against his erection. The thought caused Grissom to harden, still silent as he was in the doorway.

Nick was making some sort of guttural moaning sound now, his fingertips more erratic as he pulled her shirt from her jeans. Sara flinched a little from the touch of his rough hand on the soft flesh of her belly.

Grissom watched as Nick slowly dragged the white fabric further up her torso, exposing her slender, bare stomach. The white lace at the base of her bra was now exposed, and Grissom bit back a groan at the visual. More than anything, he wished he was the one that had her in his lap, moaning and jerking against him.

"Nick…"

"Let me touch you. Oh, God, baby, just let me…," Nick trailed off, his mouth opening against hers again, his tongue stroking hers.

Sara acquiesced with another groan, her hands tightening in his hair. Nick had pulled the shirt above her breasts, exposing the lacy bra and the pale flesh that curved enticingly above the fabric. His other hand had moved to the front of her jeans, and Grissom felt his breathing hitch, then quicken.

Nick fumbled with the steel button, and then the zipper, the metallic sound echoing loudly in the small lab. Instead of pulling back from the sudden, forward action, Sara rocked against him, forcing another revered gasp of her name from Nick.

The open zipper of her jeans exposed the front panel of her lacy, low cut underwear. Grissom knew that the sight of her as she was now would haunt all of his dreams and would be all he could think of when finding release with his own hand. She was perfect.

Nick's fingertips were tracing the flesh above the newly exposed fabric, seemingly hesitant to move forward in a mission he had started.

"Please." The small, begging tone sounded odd coming from Sara. She rocked her hips again, one of her arms lowering, her hand on his arm. "Please, Nick."

Nick made a low sound in the back of his throat, his hand disappearing under the lace. She arched back, gasping, as he found her.

Grissom groaned, the visual too much. With one hand on her breast, the other outlined underneath the lace of her underwear, her legs parted, situated as they were on either side of Nick's, it was as if Nick was exposing Sara just for him. His wonderful, smart, sexual Sara.

The sound stilled both occupants of the lab. Sara looked towards the door, blinking, her eyes still hooded with desire, but suddenly alert. Nick's hand remained under the lace, but he had paused in mid-action, his eyes wide.

Grissom swallowed, struck momentarily on what to do. But it only lasted for a second. After all, Grissom was nothing if but a man with a plan.

He walked into the dark room, pausing to close and lock the door behind him. He strode with sure, quiet steps to stand in front of his two employees, two people he valued more than most in this world.

Outside of the current situation, he would have been amused at the look on their faces. Both still flushed, both pairs of brown eyes still dilated with desire, but widened with the unexpected discovery. But he wasn't amused, far from it.

Grissom knelt down in front of them, his gaze never leaving Sara's face. She was still blinking, her lips parted in unspoken shock, exposing the gap in her front teeth he always found incredibly endearing.

"Grissom?" Her voice came out rough, almost strangled. Her hand rose from Nick's arm, and she reached out as if to touch him, but drew back, as if burnt. Grissom shook his head, a small, almost imperceptible movement. He glanced briefly at Nick, seeing the residual shock, but sudden understanding in the younger man's eyes.

Grissom leaned forward, his large, sure hands sliding against the top of Sara's jean clad thighs. She trembled, unable to prevent a small moan as the movement caused gooseflesh to rise on her arms, her belly tightening. He spared a look up at her again from the task, his usual cool blue eyes warm with emotion.

Nick's hand moved, dipping down briefly, outlined against the lace. Sara jerked, her head rolling back against Nick's shoulder, groaning something nonsensical.

Grissom's fingers encircled Nick's wrist, pulling his hand free from the confines of Sara's clothing. Blue eyes met brown, and Grissom leaned further towards the couple, taking Nick's slick finger into his mouth.

Nick cried out and Sara's head lolled back around at the sound. She watched in a mixture of shock and desire as Grissom suckled the taste of her from Nick's index finger. It was unbelievable, and she rocked against Nick's erection again, becoming exceedingly wet with the implausible visual.

"Christ," Nick was panting, watching Grissom's pale lips close around his finger, his tongue laving against his flesh. Grissom pulled the digit from his mouth, once again moving between Sara's jean clad thighs.

Grissom's cool hands were at the waistband of her jeans. He stole another look up at her. The shock was gone, but the desire was still there, made more prevalent by the raspy quality of her breathing and the flush across her face and the exposed flesh of her breasts.

"These. Off. Now," Grissom ordered, his usual commanding tone enticingly erotic in this moment. Nick's hands at the small of Sara's back helped lift her, and Grissom tugged in short, sure movements against the denim, pulling the fabric from her legs in under a minute, only pausing to remove her shoes, leaving the white athletic socks bunched around her ankles.

Grissom's hands slid down to Nick's knees, pressing them further apart. In this action, he spread Sara's thighs; her legs were still situated on either side of Nick's, her ankles flush against his calves. Grissom paused for a moment, silently savoring the visual of Sara in front of him, trembling, her milky, slender thighs spread, her sex covered enticingly by damp, white lace.

Nick's hand moved again, sliding under the lace. Sara gasped, jerking in his lap. Grissom watched the movement, his fingertips caressing the delicate flesh of her upper thighs.

"Oh…please," Sara gasped, swallowing the sudden flood of emotion that was almost too overwhelming to bear. Again Nick's finger was in Grissom's mouth as he licked the taste of her from the younger man's skin. She watched in visceral awe as Grissom pulled Nick from his lips, and then leaned forward into her.

Grissom's hands were stroking the tops of her thighs, the soft, erotic touch causing her to tremble uncontrollably on Nick's lap. Before she could gauge his action, or even think of some coherent response, one long finger had hooked the lace to one side, and suddenly she felt his mouth on a place she had desperately wished for in her deepest, most honest fantasies.

She cried out, her hips jerking wildly. Nick's hands were on her hips, and instinctively, her body fought against the hold, shuddering with the unconscious desire to be free, and the overwhelming craving that throbbed from her core.

Grissom's tongue slicked across her moist flesh, sliding down her sex, and then flicking against the bundle of nerves at her juncture. She felt the sudden intrusion of one finger, then two, and nearly lost consciousness with the overwhelming sweet bliss of her most longed for desire coming true in this small lab.

Sara's head rolled back against Nick's shoulder again. He was whispering to her, words of encouragement, promises of love, the fingertips of his left hand caressing the taut nipple of one breast. Vaguely, she saw his other hand was buried in Grissom's hair, sliding through his graying locks, pulling the other man closer into Sara's body.

She was sobbing with the heightened emotion, begging for release against the pleasurable assault of Grissom's mouth. He looked up suddenly, his light blue eyes catching her staring as his tongue flicked against her, his fingers thrusting in a raw rhythm, coaxing animalistic sounds from her throat.

"Come for us, Sar," Nick whispered to her, kissing the sweaty flesh at her throat. "Come, sweetheart. Let Grissom taste…"

She gasped, then screamed out Grissom's name, the climax tightening her body, causing her flesh to throb around his fingers. He looked up at her again, his curly hair damp with sweat, his mouth wet from her. She shuddered, feeling him pull out his fingers, and watched with unreal detachment as he slid those same fingers into his mouth.

It was unreal, the whole situation. Her body was still trembling uncontrollably, and Nick's erection planted firmly against her backside was less of a distraction then the unreadable, intently serious look in Grissom's blue eyes.

He sighed, a shuddery, submissive sound. Pushing up to his feet, his knees creaking with the movement, he leaned forward. One hand slid into the damp hair at the base of her neck, and he bent down, his lips brushing against her.

She could taste herself in his mouth, but that wasn't as shocking as the revelation of action of his kiss. His tongue moved in her mouth with a mixture of lust, resignation and love. Yes, love. She sensed it. But he was letting her go, once again.

Grissom pulled back, sparing a look at Nick. "Take care of her."

Nick nodded, watching as the older man stretched, standing to his full height. Not sparing them another glance, he walked to the lab door. Hand on the metal door, he paused, still facing away.

"Next time," he sighed, pausing for a moment. "Next time, lock the door."

Without another word, Grissom walked out of the room, closing the door behind him.