Caitlin only had six days left of her visit. Her old room down the corridors of S.T.A.R. Labs' underbelly was as clean as ever—if she needed to, she could have gone home any time. But it seemed imperative to make those last 144 hours (roughly) count. It wasn't like this trip was a vacation from Earth-1 and her usual life, but it was different, and that made it feel precious. Familiar enough that her control-freak side wasn't uncomfortable, and separate enough to spice things up.

Eddie was beside the scoreboard, still nursing his coffee from a day of sleuthing at the docks, trying to catch a gang of drug dealers that had been keeping to the shadows of the city. He had come to pick up Wally and take the latter home on his way back to the CCPD. Of course, both had stayed for a last-minute mission involving a car chase and some hand-to-hand combat—with a driver that had some strong feelings about doing time for his theft.

The two younger men found the idea of their tightly-wound bioengineer and brooding leader engaging in a petty bet hysterical. Stein, the champion of propriety and professionalism to the last, seemed almost embarrassed by the flirting and the competition for the first few days, avoiding comment. Then he'd revealed—with a sudden shout during Savitar's harrowing fight with some kind of Cat Woman wannabe on Wednesday—that he was just as interested in a winner as everyone else was.

"All tied up," Eddie announced, tossing Caitlin the marker.

Caitlin caught it, clumsily, and hurried to the glass to squeak out a new tally beneath her name. "I never thought I'd be glad to hear about a sprain to the wrist." She paused, frowning, cap halfway to its seat. "That's not violating the Hippocratic Oath, is it?"

"Sorry." Eddie stirred his coffee up with a twirl of his hand and winced. "You're asking the wrong guy."

"I didn't sprain anything."

Caitlin and Eddie both jumped; Savitar had entered silently this time.

In a rush of wind, Eddie's drink was suddenly in the speedster's hand. Savitar didn't bother waterfalling as he downed the last of it.

Eddie gave no reaction, instead blinking in confusion from Caitlin to the hero. "You said your punch went wrong."

"I heard it," confirmed Wally, coming in with a stack of paperwork from his internship. There was ink all over his shoe and left thumb.

Savitar shrugged. "I guess it healed on the way." He was looking at his personal physician out of the tops of his eyes, unblinking.

"No," Caitlin scoffed, arms folded tightly across her chest. She glowered at him, head sunk slightly below her shoulders. Her mouth made an O of indignation. "No! You made it up! Unbelievable."

All heads turned in her direction at this, the most frightening of tones. They were instantly transformed into a group of brothers being called inside by their mother, who had no doubt found the mess they'd made in the house. She whipped around and wiped the tally mark away from her name, fuming.

Caitlin's words were clipped, just laughably short in her anger. "Lying to intimidate the competition? What are you, twelve?"

Savitar used his powers to get right in front of her, grinning. "Now," he said slowly, reaching over her shoulder to pick up the marker. "Is that any way to talk to a patient?"

She turned to follow him as he moved to add a point to his own side. "You're not my patient until you're actually in need of physical care."

He was enjoying this, tone the same old blunt, raspy wave, but there was a childlike spark in his eyes and the corners of his mouth. His face wasn't expressive in the same way Barry's was, but it had its moments.

"I'm in need of dinner," he told her curtly, spinning on a heel to walk backward past her. "Does that count?"

"Get it yourself," Caitlin huffed. "Blast away to Italy for all I care!"

"Dang," said Wally. Eddie drove an elbow into his ribs. Their usually-calm consultant was unwinding, and this was no time to interrupt the fun.

Savitar lifted Eddie's coffee to his lips, nodding in a very agreeable way as she derailed.

"This close," Caitlin went on, showing the distance between thumb and forefinger. "I am this close to beating you and getting us that upgrade."

She snatched the coffee from the desk where he'd set it down, heading for the trash can absent-mindedly. When Caitlin was on a roll, her body moved on autopilot to the nearest task in need of completion. It was clear that Savitar wasn't happy with her choice in task.

"With all the unknown metas this Earth has, an acid repellant is the least you could do—"

"Caitlin—"

"My end goal, Savitar, is to help you on the field. All this over a technological advance! And you can't even fight fair—"

In a flash of sickly-yellow lightning, he had grabbed her hand before she could toss the coffee cup.

Savitar pulled her in and gently pried the half-empty cup from her angry, angry fingers. "I want my coffee."

It was such a Barry Allen thing to say, she lost her train of thought and went for squinting up at him instead, trying not to think how silly she had sounded in the past ten minutes.

"Show's over," Eddie muttered to Wally.

"I gotta get these copied anyway," said West, waving the papers. "Doc says they're due tomorrow. I busted a pen."

"Come on. You can use the machine at the station." Eddie placed both hands on the shoulders of the smirking youth and guided them both out the door without a goodbye. It was late, and from the melting-ice expression on Caitlin's face, there would be no more off-the-handle outbursts to enjoy.

Caitlin kept squinting at the former God of Speed. "Your wrist doesn't look sprained to me," she said.

He moved the now-free, coffee-catching hand to entwine with hers and tightened his grip, feigning a pout and nodding again. "I think I need some painkillers."

"Don't try to be cute, Savitar," she sighed, rolling her eyes. Her voice went dry and tired, the fight leaving, the exasperation sticking its foot in the door. "Anesthetic goes right through you."

"Or a burger."

"Changing the subject?" Caitlin turned sulkily to the monitors, shutting them down one by one. Nightly custom. "I'm adding a new rule—lying to lull the other party into a false sense of security docks you a point."

"Caitlin," Savitar reiterated firmly as she tugged her hand away. "I want food."

"Then—go get some!" She flung out an arm to shoo at him. "You have super speed. I'm busy; who do you think has to turn everything off for the night? Some of us move in normal time."

With a black blur around the corners of the Cortex, a slight wind at her back, and barely a sound, the room was mainly dark. All technology had been powered down. The only light came from her snowflake pendant, and one or two emergency beams in the corridors.

She felt him leading her out into the hall where they could see.

On the floor was several bags and cups from Big Belly Burger. Evidently he'd had time to obey her during his jaunt to turn things off. Savitar let go and slid with his back against the wall into a comfortable position, unwrapping the first burger.

Caitlin sat with a ginger removal of the heels across from him. "You," she said pertly, reaching for the banana milkshake, "are very stubborn."

Savitar spread the palm that wasn't occupied, eyebrows bouncing, a tiny smirk lifting the chewing mouth.

"I was thinking," she added more seriously, dipping a fry in the shake. "Cisco's outfitted the Flash suit with so many extra features—night vision, water shoes, a heating system—when we add the repellant, we could add a few other things. It never hurts to be over-prepared. And you don't want to have to break between patrols to keep patching it up."

She was met with a long-suffering sigh.

"I installed night vision already." Savitar swallowed the last burger—about sixteen wrappers lay in a pile beside him. "And the heating fibers in the fabric."

"You did?"

"Couldn't sleep."

"When?"

Savitar tossed the thirtieth wrapper aside. "About a month ago."

Caitlin set down her milkshake, eyebrows lowering. "Then…why not just add the repellant yourself? We don't even need the record, we could just—"

"I like the record, Caitlin." Savitar laced his arms behind his head. "Because this way, if I win, you stick around."

She allowed a smile. "So that is the 'grand prize'."

He didn't answer or nod, he just watched her with mismatched eyes that got gradually softer. It made him look more like Barry when she first met him, bright and eager and warm and ready to use his powers for the greater good. Ready to help and love anybody. But all that warmth was being directed, this time, at just her. It should have been overwhelming, but it was starting to feel correct and regular, like coming home to a new apartment after a week away.

She stood and stepped over the picnic to sit beside him. After a moment or two of silence, the emergency lights flickering above them, she asked, "How often do you go without sleep, Savitar?"

There wasn't a quick response this time.

"It's not…still the Speed Force nightmares, is it?" Caitlin chewed her lip, nerves mounting as she waited for confirmation. Some things, science and medicine couldn't fix. Some things had consequences without cure.

A tiny snort escaped him. "I don't always have my buffer."

Recognizing one of her many titles, she draped her arms across pulled-up knees and smiled again. It wasn't something she should smile at, but one always appreciated being needed. "You're blaming me?"

"Hey, if the lab coat fits." He took her hand—it was always cold, and he had developed the habit, sometimes, of vibrating his own to warm her up. The side effects of being Killer Frost had their perks. "Stop," he said suddenly.

"Stop what?"

"Worrying about me."

She was quiet for a moment. She thought of a million ways to answer that. But in the end she went with a slightly-teasing, obstinate, "No."

A louder snort, one that was usually followed with short, hoarse laughter. Barry's it's-too-early-in-the-morning laugh, but for Savitar it always sounded too early.

"I'll survive acid." He leaned his head back against the wall and closed his eyes, the adventures of the day finally showing on his face. "I don't need water shoes. And I can take nightmares. So there's no point worrying."

"That's a shame," muttered Caitlin, glancing in a distracted way down the corridor, as if there were anything else to see. "I do it so well."

"Cait."

"Hmm?" She whipped back toward him.

"You add the water shoes to the suit," he said groggily, "you stay another week."

"You can't add stipulations. And it's not like I can do it myself. I'm no Cisco," she said, nudging a Big Belly Burger bag with her toe to see if there was any weight left to it. He'd emptied them all. Suddenly it was too quiet. "Savitar?"

He still had his eyes closed, breathing evenly as he sat against the wall. His hand was a little limp in hers. Had he fallen asleep? He must have gotten less rest than she'd thought. She'd have to start getting up and checking on him in the night; maybe she'd catch him tinkering with his tools instead of sleeping. Just like old times.

If Cisco or Harry or Joe were here, or even the team on Earth-66, they would help her force the speedster off to bed. But it was just Caitlin, and she knew him. If she stayed, he'd sleep here all night. If she stood and went to bed herself, he'd wake up eventually and make his way to his own room, collapsing and hopefully getting through the night well enough to be ready for action the next day.

Only one of those options involved him eventually making it to an actual mattress, which was the one she'd pick if she was the competent personal physician she claimed to be. However tempting it was to relax beside him, sitting there in the corridor all night with the dim emergency glow, too easy to pretend time didn't exist and she wouldn't be going back to work in a few hours.

Rolling her eyes in resentment toward her own practicality, Caitlin moved to get up very slowly. She almost made it to a full crouching position, but Savitar's grip on her hand tightened in an instant.

"Two weeks," he repeated without opening his eyes.

For a few seconds she smiled at his dormant form. "Do you ever give up?" she sighed at last.

"I learned from the best." He blinked awake and with one nonchalant tug, she was back sitting beside him, off-balance.

"You know I can't stay that long." Caitlin resituated to a more comfortable position, resigned to the hallway option. She could do worse than spend one night sitting beside a friend in danger of nightmares. "Besides, Wally's interning in a medical wing. Professor Stein has five PhDs. This team doesn't need a doctor from another Earth 24/7."

"I didn't say anything about the team." Savitar glanced down at her, voice matter-of-fact, casually adding, "I need you more. Barry can wait a while longer to get you back."

"I'm his physician," Caitlin argued weakly. He smelled good and his sleepiness was contagious; she let her own head mirror his, bumping it against the wall. "If he gets injured, you know better than anybody I'm one of the only people in that building who can patch him up. A real hospital asks too many questions."

"The other Flash gets you if he takes a bullet," Savitar grunted. "I get you for the rest. That should be the deal."

"He's not invincible either, Savitar. I thought we agreed this wasn't going to be easy. It's not like I can live here. My life is—"

"On his Earth. I remember." He chortled bitterly. "Guess I'll have to settle for visitation rights."

"When you put it like that," Caitlin let out a quick laugh. It sounded odd in the otherwise-silent Labs. "You make it sound like I'm legally obliged to be here."

"Not on paper," he returned.

"I'm here because I want to be." She squeezed his hand. "And you know it."

"I could use a reminder," Savitar muttered. "You know how I like to tune other people out. I could forget." He turned his head toward her, eyebrows raised.

"I think a burger session in the hall at—" she lifted his hand up to check his watch. "—12:45 AM is enough of a reminder."

"Only if you don't move." His eyes slid shut again.

She grinned. "Deal."

There was more silence, and her own eyelids were feeling a little heavy, but his hand was as tight and awake as ever in hers. It kept her from nodding off.

Then: "Give me your milkshake."

"No!"

"Ten thousand calories a day, Doctor Snow."

"It's so far away. I refuse."

"My foot's asleep."

It was surprising how much he could sound like his Earth-1 doppelganger when he wanted to. It shouldn't have been—given his biology—but he worked so hard, so often, to be separate, Caitlin could always appreciate it when the real Flash shone through.

"You—" she staggered up and snatched the half-full cup from the floor, plopping back down with an exaggerated huff. "—are completely impossible."

He took it and blinked like a puppy woken from its nap. A wolf's puppy, more accurately. "Lucky for me," he replied before taking a sip, "I hear you're good with the impossible."