A/N: Just a little something I had to get down on paper because it was interfering with that mammoth other work of mine which shall remain nameless. :-) This is pure, unadulterated fluff. Consider yourself warned!

Spoilers: None

Disclaimer: Sure, I own CSI:. And, clearly, I'm masochistic because I continue to allow my own writers to torment me with the lack of resolution between my two favorite characters. I should really seek professional help. :-)

Caught in the Inertia

He'd never disliked birthdays, necessarily, just never really thought much about them. Even as a boy, when his classmates had excitedly passed out party invitations weeks beforehand, he'd just cocked his head and looked on in befuddlement. After all, birthdays weren't unique. Everyone had one.

Perhaps that was the reason his hand hesitated in its path toward her door. Or perhaps it was the fact that he looked the very picture of insanity, holding 35 candle-adorned cupcakes with his forgotten work badge still dangling from his neck. Or perhaps it was simply the fear that welled up when he allowed himself to ponder the emotion that drove him here.

Regardless of the reason for his hesitation, he knew what propelled his knuckles against the cheap wood paneling. It was the sparkle of unshed tears in her eyes as she'd bade him goodnight earlier and the tightness in his chest when he'd registered the significance of the date on his desk calendar. He steadfastly refused to believe it was anything deeper than that.

Sara blinked in surprise at the sight that greeted her when she opened the door. After all, it wasn't every day that her boss even acknowledged her existence, much less came calling with a huge cardboard box filled with cupcakes. "Grissom?"

"Happy birthday."

His expression was caught somewhere between tentative hope and vague nausea, and she wasn't quite sure what to make of it. But his simple pronouncement was accompanied by an unsure nod toward the box, and she swallowed hard at the unexpected sweetness of the gesture. Her smile was wide as she stepped back and beckoned him inside.

Grissom looked utterly out of his element, and she watched in amusement as he searched uncertainly for a surface large enough to hold the box. At last, she shoved aside two forensic journals and her TV Guide to allow him access to the coffee table. Curious, she sat on the couch and smiled when he followed suit.

"Thanks," he murmured absently, and her eyes grew wide when he fished a lighter from his pocket and meticulously set each candle aflame.

When he finished the task, he looked up, and his breath caught in his throat. Mesmerized by the flames and awash in their flickering glow, Sara was undeniably radiant, and he wondered at the spell she had cast upon him, at the magic that almost coaxed three forbidden words from his lips.

Almost.

It was her eyes that broke the spell, for they were once again full of tears, and he watched them close an instant before a lone drop began its trek down her cheek. And that pang in his chest was back, that suffocating squeeze of guilt and remorse and some other feeling he could not – would not – name.

Dejected, he stammered, "Sara, I-I-I'm sorry. Catherine always used to… do this… stuff. Now that she's on swing, I…" He sighed as he lowered his eyes to the cupcakes, chocolate icing melting a little in the heat. "I didn't mean to forget your birthday. They've just never been that important to me, and I guess… I forgot how important they are to everybody else…" His voice trailed off, and even he realized how pathetic an excuse it was.

But Sara didn't. Because she was leaning forward to blow out the candles, long tendrils of wavy hair held away from the flames by one delicate hand. And she looked like the weightless rush of his favorite coaster and the innocent laughter of playing children and everything good in the world.

He smiled, and that was what she saw when she turned to face him. Thirty-five candles had stolen all but one last breath, and Grissom's genuine smile took that from her. He was a little boy again, and it was a better gift than a truckload of cupcakes and candles.

Sara was tired, so very, very tired. Of all of it. Of denying her heart, of doing exactly the opposite of what she wanted. Of pretending she didn't love him.

But, somehow, the boy who stared back at her didn't look like he would mind if she acted on impulse, and so she leaned forward and set her lips on a direct course for his cheek. It was just supposed to be a simple thank-you.

She didn't factor in Grissom turning his head at exactly that moment, and she certainly couldn't have predicted the flawless alignment that saw her lips meeting his in one life-altering instant. But the collision was surprise and longing and utter perfection, and she couldn't bring herself to pull away.

And neither did Grissom.

Sara knew Newton's laws. She understood that objects at rest stay at rest until acted upon by outside forces. She was well aware of the forces that had kept them at rest for years, of the mutual attraction that drew them to each other and the counterbalancing repellent effect of his fear. She could feel the attraction in the way he tilted his head to deepen the kiss, in the pounding pulse of her own heart.

What she couldn't feel was the counterbalance. Bodies in motion, that's what they were now. But they'd never been in motion before, and she was terrified by the inertia.

She pulled back abruptly, dropped her eyes to the table, busied herself with pulling candles out of the cupcakes and working out the physics in her head. Too close. The attractive pull is too strong when you're that close. It overcomes the repellent force. One… Two…

Now that they were separate bodies again, she awaited the return of the resistance, anticipated its appearance. She'd lived with his fear for so long now that it was a part of her, too; it permeated her soul, her life, seeped through to her bones. But still, she felt its loss, this dearth of the forces that normally kept them in stasis. And still she removed candles, their waxy stalks resisting the movement, wanting to remain at rest, envying her, envying Grissom. Seventeen… eighteen…

She couldn't look at him, couldn't bear to watch the fear return, to see Newton in action. Her eyes remained firmly fixed on the cupcakes, chocolate icing dripping from the candles like tears. Thirty-one… thirty-two…

"You forgot one," she said and extended the last cupcake to Grissom, its deep brown frosting unmarred by Newton's laws.

"No, I didn't. I bought three dozen, but you're only 35. I couldn't make you a year older just because the store was unable to accommodate a number not evenly divisible by twelve."

Sara knew it was a mistake to look at him, she really did. But she'd made so many mistakes already, and she couldn't seem to stop herself from making more.

His eyes were smiling, even if his mouth wasn't, and it only took her a second to realize that their bodies were still in motion.

She smiled back at him then, ignoring the prickle of tears and the unfamiliar rush of giddiness. And chose to press ahead into uncharted territory. "Why don't you care about birthdays?"

Sara at rest would have remained still as she awaited his response, would probably have not asked the question at all. But Sara in motion leaned forward, eager, hungry.

He shrugged. "I never have. They're not unique."

"But yours is," she responded, and he cocked his head in confusion. But she just grabbed the lighter and fashioned one last birthday cupcake, its candle standing tall and proud as she handed it to him. "Because it's yours."

He took it slowly and stared into the flame, entranced until Sara's gentle command broke the spell. "Make a wish, and blow out your candle."

He did and, when the flame was no more than a wisp of smoke curling high above them, she asked, "Do you think it will come true?"

"No." He shook his head even as he leaned toward her, enjoying the way her stare widened as the distance between them decreased. "I think it already did." And he took pleasure in how her eyes got impossibly bigger at his words just before he set his lips on hers again.

In later years, the story varied with each narration, and Sara always smiled whenever he told the twins how their grandmother had enchanted him with her kiss. And then she felt the magic he described when he whispered, "She still enchants me," just before his lips met hers. And the roaring in her ears was always louder than Brandon's hearty "Eww!" and Katie's innocent giggle.

But she knew the truth. In reality, there was no magic, just simple inertia. Bodies in motion remain in motion. Newton had never been romantic, but he'd always been right.