Author's Note: Spoilers for episode 4x01, "Unwritten Rules." This is a sequel of sorts to "While the Heart Beats," but easily stands alone. Enjoy!

Heart-Stopper

"There's a drum line in my heartbeat
I know exactly what it's from
They're turning off the street lamps
They say the day is almost done..."

- 3OH!3, "Back to Life"

Some of the coldest nights of Jamie Reagan's life had been working midnights his rookie year with Renzulli, because the sergeant kept the car off for at least forty-five minutes of every hour. "What, you cold? What'samatter with you, Reagan? I'm burning up," he would complain, stripping off his jacket even as Jamie trembled in the passenger seat, hands jammed in his armpits and wishing he could throw on an extra kevlar vest.

Two winters later, he'd spent the same endless dark nights with Vinny, but he'd never gotten cold on those tours. Not with Vinny's motor mouth.

"Y'know one of the things that surprises me, Reagan?"

Jamie had been slumped in the passenger seat, rubbing a hand over his eyes and pressing down hard to stay awake, so hard he saw bursts of color against the backs of his eyelids. "That the human stomach isn't designed to hold more than two hot dogs at a time?"

Vinny eyed him. "You serious?"

Jamie grinned. "Tell me what surprises you."

Vinny put his eyes back on the empty road in front of them, watching as an old man eased across the street and the traffic signal hung a bored red. "It always surprises me how fast these freakin' thieves can run. Y'know? I mean, they go from a dead stop, crouched down stripping hubcaps off a car or crackin' the door or something, then in two strides they're tearin' off like the Road Runner. 'Beep-beep' speed, y'know?" He grinned at Jamie. "Two, three, four blocks down the road, they're nothin' but a blur, just enough to duck into some alley or doorway someplace, and boom. Vaporized."

"Uh-huh."

"That doesn't surprise you?"

"Fear makes people do crazy things." Jamie ran his hands briskly over his arms, rubbing them hard to burn off the chill.

Vinny looked over. "Cold?"

"I'm fine."

"'Cause I can turn on the heat, but you know what idling cars do to the ozone layer."

"I'm fine, Vinny."

"All right." He leaned back in his seat, easy grin returning to his face. "Thieves, man. They got, like, secret jet packs or something. Maybe superpowers."

"Superpowers," Jamie repeated drolly.

"Yeah, man. The first time I saw some punk tear off, I tell ya, I didn't even know what was happening. Some goofball tryin' to break into a Camaro, my partner and I lit him up, and kapow!" Vinny smacked the steering wheel, the sound like cracking ice in the cold air. "Beep-beep speed, man. Beep-beep. Wile E. Coyote on his way."

Many a midnight shift had passed in similar fashion, although the consumables changed with the season. Coffee for the winter nights. Bottled water during the summer days. Vinny had even bought him a chocolate ice cream cone once, and told him about the time he'd caught a Mr. Softee man selling weed out of his truck along with popsicles and ice cream sandwiches.

Grinning despite himself at the memories, Jamie leaned back against the side of his patrol car outside the 12th. A styrofoam cup of coffee was in his hand, and he looked down at it, mind wandering.

He'd been drinking a lot of coffee lately, as hot as he could stand it.

He was always cold, anymore.

"What did you say that was, Reagan? A mocha? Didn't your daddy teach you that cops drink real coffee, dude?"

It had been almost four months. Renzulli had gone back to flying his desk after two, and Jamie's squad had become a regular stop for any 12th precinct guy whose partner was sick or on vacation. Even he had to admit, it was high time he picked up a permanent partner, even though the thought turned his stomach a little. It was selfish, but part of him really didn't want to move on. It was stupid, but a new partner in that seat - a partner; not just a warm body, but a partner - dishonored Vinny's memory, somehow. It was Vinny's seat, next to him in 7554. It ought to always be.

The sudden impact was a hand grenade shattering his shoulder, a garbage truck mowing him down. He was on the ground before he even knew what had hit him, twisting onto his stomach in agony, his chest a fiery mass of pain...

Vinny was always with him anymore, like a shadow in the corner of his eye, or a whisper in the back of his mind. Anything, everything brought him back. That stupid song on the radio about how to revive a dead party. The smell of that peppermint coffee Vinny had never admitting to liking, from the food truck on twenty-third.

A hail of bullets, screaming through the air, chewing into concrete. Jamie dove behind the wall for cover, moving on instinct, when he realized Vinny wasn't at his side...

Not a day went by that he didn't think about it. Not a night went by that he didn't dream about it. Vinny was a hollow place in his chest, a phantom ache in his shoulder.

Time heals all wounds, they said. He was still waiting. Probably always would be.

"You know what else surprises me, Reagan? The places these creeps hide their guns. I mean, I found one once in one of those huge Triple Fat goose down jackets, y'know? Hinged door panels. Even the air bag compartment in the car, man. What's up with that? What happened to the days of a bad guy just stickin' the lead in his waistband, man?"

"Hey... you Reagan?"

The young woman's voice surprised him, and he glanced up to see a young officer approaching him, petite and blond. Her crooked smile was tentative. "Eddie Janko," she said, slipping one hand out from behind her hat as she approached. He shook it without thinking. "Sarge says we're, uh... we're riding together."

Her grip was strong, and her hand was warm. Jamie had to force himself to release it, and stared at her openly. He'd been expecting a new partner, sure, but no one like this.

She stared back, mistaking his surprise for distaste. Hesitation flickered in her eyes. "Something wrong?"

"No, um... I was expecting a-"

"Fat, sweaty, Hungarian guy?" The words rolled off her tongue so easily they seemed almost practiced. "Sorry to burst your bubble."

He gave her a tentative smile of his own. "No offense," he offered lamely. The warmth of her hand lingered in the palm of his own.

"Oh no, trust me, it's really hard to offend me." Her easy smile was back. "My real name's Edit, after my grandmother, but Eddie's just easier all around."

Jamie nodded. "Okay. Uh, who was your last partner?"

"Actually, I just graduated from the academy last week," she said proudly.

Jamie waited a beat too long for her to drop the punch line. Silence stretched. "Oh, seriously," he finally said, blinking stupidly again.

"You're my first, Reagan," she grinned. "Be gentle."

Jamie hesitated, then decided to ignore that. "I just meant, all my other partners have had at least as much time on the job as me." He shrugged.

"How much time is that?" She combed her fingers through her hair, tucking an errant strand back into the bun at the nape of her neck.

He tried not to watch. "Three years."

"And how many partners?"

"Two." He nodded toward the precinct behind them. "And Sergeant Renzulli was my first, so consider yourself lucky."

She laughed. "I think I do."

He smiled back at her. It felt good, but uncertainty lingered, a cool shiver in the pit of his stomach.

"God, Reagan, what's the matter with you? You have officially been upgraded in the partner department, my friend, and you know it's true if even I'm sayin' it. Hell, if I knew this one was on the lineup I would've killed you."

"Shhh," Jamie muttered distractedly.

Eddie frowned at him. "What?"

He was saved by the crackling radio behind him, whose dispatch suddenly grew urgent. "All units, 10-13 from the officer."

Eddie's startled eyes met his. Her grin faded.

"Shots fired. Corner of three-two and ninth. Units responding."

Jamie's grin faded, too.

And the cold was upon him again, like ice, cracking him from the inside out.