A/N: My first story for Criminal Minds. I've recently taken an interest in writing about the developing friendship between Aaron Hotchner and Spencer Reid, and its gradual maturation into something more. This will probably start as a series of episode tags, but hopefully there will be long-form stories later on.

Episode tag to Season 1, Episode 6, "LDSK." Reid and Hotch centric, friendship - maybe very, very pre-slash.

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It took Aaron Hotchner almost a full minute to notice Spencer Reid hovering in the doorway of his office, fidgeting with the corners of his files. The oversight wasn't like him—normally he was aware of his visitors' footsteps before they even stepped into the room, already making preliminary judgments about mood, apprehension, intent, and level of agitation before he ever lifted his eyes from his work. He was especially aware of Reid, ever since Jason Gideon returned to active duty and his protégé formally joined the BAU team; though he was older, more established, Reid seemed even more precarious now than he had when Hotch first met him, almost four years ago, the brilliant young man deliberately cloaking himself in Gideon's shadow. Hotch didn't like to keep Reid waiting at his door. But it was very late—late enough that the papers on his desk had begun to blur, and he found himself largely staring at them unseeing, trying to disentangle the whirls and loops of distorted ink—and it had been a long day for all of them. Hotch let his self-recrimination go and set his pen down, giving the younger agent in the doorway his full attention.

"Reid." The name didn't come out quite the way he meant it to—less like an invitation than a command for a status report. Hotch settled in his chair and folded his hands, softening his tone as he tried again. "Do you need something?"

Reid's eyes darted away from his, a little bloodshot, his brown irises dulled by the dark circles around them. He seemed jittery, off balance, and Hotch leaned back in his chair, scrutinizing his subordinate. The pad of his thumb scraping restlessly over the edges of the files—just one too many cups of coffee, or was there something more going on? He watched Reid's face for any tics or microexpressions as he spoke.

"I just wanted to give you these? I finished my review report and my statement about the shooting."

Reid flinched as he said the last—but a door slammed across the office at the same moment, and Hotch couldn't be sure whether it was the words or the sound that had made him jump. Or perhaps it was the combination. Hotch shook his head. "Reid, you didn't have to stay and do those tonight."

"Neither did you," Reid pointed out, shifting his weight and nudging a wayward strand of hair back behind his ear.

Their situations weren't really the same. The papers on Hotch's desk were reports for superiors, people higher up the chain who didn't understand taking a night to decompress before recounting the details of every case in their chilling particulars—caliber of bullets, number of casualties, fatalities, the exact number of hours between when the BAU jet touched down and when the suspect was apprehended. Whether anyone had fired their weapon. Hotch glanced down at the PPSS Psychological Fitness-for-Duty Evaluation Form, on which he had been meticulously detailing why Reid didn't need to be sanctioned or assigned counseling even though he'd killed a suspect after failing his firearms qualification. He slid it carefully under the rest of the stack and looked up at Reid again, choosing not to argue with him.

"Go home, get some rest," he urged, nodding toward the bullpen, where Derek Morgan was probably loitering, waiting to drive Reid home as he usually did after difficult cases. "I'm sure Morgan's ready to leave, too."

"Actually, he already took off," Reid admitted, leaning gingerly against the doorjamb. "I told him I had some things to take care of first, so he should just go."

Hotch frowned, sitting up a little straighter. "And how are you planning to get home?" he asked, holding eye contact with Reid and hoping the younger agent would pick up on the underlying assertion—that he was absolutely going home tonight.

Reid shrugged. "The last number 17 bus comes by at 1:13 a.m. and the last 48 bus isn't until 2:11. Sometimes it's more like 2:24 if it has to stop at the railroad tracks for the 2:07 train." Reid almost seemed to smile, but then his gaze dropped, as if unable to meet Hotch's eyes. "I take the bus a lot. It's not really that big a deal."

Hotch knew it wasn't. Part of him—the rational part—knew that for all that he sometimes came off as young and socially insecure, Reid was an FBI agent, one of the most remarkable he had ever worked with, and he was entirely capable of taking the bus. But there was another part of Hotch that didn't want to imagine Reid hunched into his too-large jacket at the back of the bus, leaning away from the profanity scratched into the plastic seatback with somebody's keys—not after this case, of all cases. Not when he was leaning back against the doorjamb with those dark circles around his eyes and his arms wrapped just too tight around the files, like he was searching for something to hold onto.

The nervous babble of Reid's voice signaled he'd been quiet too long.

"Did you know only 2.52% of commuters in the U.S. take the bus?"

Hotch gave Reid another considering look, and then pushed up out of his chair, feeling the stiffness of sitting too long ripple down his legs as he gathered his papers. "What's the percentage who carpool?" he asked.

Reid blinked. "12.19. Why?"

Hotch shook his head, a brief smile crossing his lips as he slipped into his heavy overcoat. "Come on, Reid. I'll give you a ride home."

In the car, he let Reid do most of the talking. Hotch kept half his attention on the road and the other half on his colleague, listening for any hesitation in his voice, any incoherence or loss of details. He spent the twenty seconds they sat parked at a stoplight trying to decide if Reid's hands were shaking or if that was just the vibration of the engine rattling up through him. He had heard Gideon on the plane, assuring Reid that he would feel it later, the effect of killing someone—knew that Gideon believed Reid could handle it by himself. Gideon was probably even right. But could and should were different things.

He had always trusted Gideon to know what was best for Reid. But now—since Boston—Hotch just wasn't quite sure.

About twenty minutes later he parked in the dark lot of Reid's apartment building and turned off the car, neither of them moving for the doors just yet. It wasn't the first time Hotch had seen Reid's building, but somehow it struck him all over again: the barrenness of the wood siding, the peeling paint on the trim around the windows. One of the bulbs in the stairwell was out and the shadows fell heavy across the landing, darkness lurking in the corners. Hotch watched a plastic bag blow across the desolate parking lot. Reid scrunched down in the passenger seat, pulling his messenger bag against his chest.

"You could come in for a minute. If you want to. I, um…" A hesitant smile, the kind Reid wore the most often, just at the edge of self-deprecating. "I have a really nice coffeemaker."

Hotch scanned the dark rows between the silent cars, found Reid's eyes and offered a little smile of his own. "Coffee sounds great."

Reid hadn't lied about the coffeemaker. Aside from his computer, though, it was the only nice thing in the apartment—everything else looked as though it might have come to him secondhand, or just been left behind, unwanted, by the last tenant. As Reid busied himself with the coffeemaker, Hotch stood in the living room and took in the battered furniture, the uneven blinds, the heavy cathode-ray television listing on an end table he thought he remembered Penelope Garcia trying to get rid of several months ago. Though it wasn't dirty, there was an aura of neglect hanging in the apartment, as though the person who lived there was rarely home, or didn't consider this a home. The profiler in him supplied conclusions automatically—high-functioning, socially isolated, difficulty building and maintaining relationships. It was disconcerting to consider Reid so distantly.

The couch, a faded copper-orange fabric in some kind of corduroy, was piled waist-high with books, stratified like geologic layers, half of the books open as though they had been set down mid-perusal and never retrieved. Somehow there were still enough books to be filling the entire floor-to-ceiling bookshelf. Hotch lifted one from the top of the pile and flipped it closed to read the spine. The Audubon Society Field Guide to North American Butterflies. Reid leaned out of the kitchen far enough to catch his gaze.

"Did you know 35% of Americans prefer their coffee black?"

"I'm one of them," Hotch told him, setting the book down again. Reid smiled.

"I know."

Hotch followed his retreating colleague into the kitchen, taking in at a glance the old white refrigerator, the dish strainer holding only one plate and a few stirring spoons. "And how many people take their coffee with a quarter cup of sugar?" he asked, keeping his voice light so Reid would know he was joking.

"Actually, I don't think anyone's ever done a study on that. Though I am one of the 24 million people who have more than thirteen cups of coffee a week." The surface of the coffee trembled as Reid held out his mug, and even though his expression was clear Hotch was certain now, as he accepted the coffee and their fingers brushed, that Reid's hands were shaking, just a little, just enough to send a lone drip of coffee over the rim. It left an ugly yellow stain down the curve of white ceramic.

Hotch studied his face, searching for any clues to what was going on inside Reid's head. But there were so many reasons his hands could be shaking—lack of sleep, the late hour, thirst or hunger or the last dregs of a caffeine high he was about to reinvigorate. Even after all the years working together on and off, he still didn't know enough about Reid to assume anything. Reid turned away to grab the sugar bowl and Hotch took a sip of his coffee—a dark roast, smooth but bitter on his tongue—and reached up to open the cabinets. They hadn't had a chance to eat much all day. Maybe a meal would do something for the tremor in Reid's hands.

The only things in the cabinet were a box of saltine crackers and a can of mushroom gravy. Hotch shot his colleague a look. Reid shrugged.

"I don't really do much cooking. And when I buy groceries, they usually just end up going to waste, so…" Reid leaned back against the counter and crossed his arms, and Hotch couldn't stop himself from cataloguing defensive posture, uncertain body language, unease. "It's okay. I don't usually eat this late anyway, so…I'll just have a little extra breakfast tomorrow." Hotch tried to remember a time he'd ever seen Reid eat breakfast at all.

Careful not to spill again, Hotch set his cup of coffee down and leaned into the counter opposite Reid, stealing a glance at the glowing clock on the microwave. He hadn't intended for his offer of a ride to end up this way—hadn't even intended to come inside. And it was getting later all the time, to the point that he might as well just drive himself back to the office and sleep in his chair, instead of wasting what few hours were left in transit. But he couldn't imagine leaving now, knowing that Reid would drink another cup of coffee on an empty stomach and then perch on the patchy armchair in front of the TV and sleep a few hours, maybe, between the static of infomercials and bad dreams. He didn't want to abandon him to that. Hotch consulted the clock again and then straightened, fishing his cell phone out of his pocket.

"Well, I guess we have no choice but to order a pizza, then."

Reid choked on a sip of his coffee, and then he almost laughed, wiping the back of his mouth with one hand. Hotch raised an eyebrow and the younger man ducked his head, fighting a smile. "Sorry, I just, um…I've never seen you eat a slice of pizza before."

"Never?" Hotch echoed, deadpan, though he thought the twitch at the corner of his mouth probably ruined the effect.

Reid shrugged. "I'm pretty sure I'd remember."

"Well, I assure you it's happened." Hotch took a step forward, the motion pulling Reid's eyes up to meet his again. "What about you, Reid?" he asked, quirking an eyebrow. "Do you eat pizza?"

Reid looked down at his cup of coffee, toggling the handle with the pad of his thumb. Then he looked up and smiled. "Did you know the average American eats forty-six slices of pieces every year?"

Hotch tipped his head to one side. "I'm pretty sure I haven't reached my quota yet."

It had been a long time since he'd ordered a pizza, but Hotch found he hadn't forgotten how to do it. In the thirty-five minutes they spent waiting for its delivery he and Reid finished off their coffees and then cleared the couch of books, and though the cushions were lumpy and misshapen from weeks (months?) of uneven weight, Hotch didn't say anything about it when he sat down and felt the hard post of the center support under his tailbone. While Reid fiddled with the remotes for the TV and an old DVD player he stepped into the hallway and made a call to Haley's sister, Jessica, to let her know he wouldn't be able to swing by the hospital until tomorrow. He could hear the reproach in her voice as he explained about a coworker who was in a bad way, the unspoken edge demanding who could possibly need him more than his sick wife, laid up in bed pregnant with his first child—but the fact was, Haley had her, and the doctors and nurses and his mother-in-law, and Reid was so alone. He hung up on her a little too sharply and went back inside, let Reid tell him about the old sci-fi show playing on the TV, a series he'd borrowed from Garcia, and how many pounds of pepperoni were consumed each year on pizza alone.

For an hour he did nothing but sit forward on the lopsided couch and eat modest pizza to a black-and-white TV show he couldn't follow, and watch as Spencer Reid relaxed, a little bit at a time, into the well-worn curve of the armchair, his long legs pulled up in front of him and his paper plate balanced on his bony knees. Hotch had never seen him more at ease than he looked curled up in the pale light, his eyes half-lidded, laughing in between bites. Hotch even found himself laughing once or twice. Nearly every line of tension was gone from Reid's body by the time the second episode cut to credits and Hotch got slowly to his feet, rolling his stiff shoulders and gathering their used plates into the pizza box. He stopped as Reid's soft voice reached out to him through the semi-darkness.

"Hey, um…Hotch?"

Hotch turned, obliging, and met his eyes, studying the wrinkle of uncertainty bothering Reid's forehead. Reid shuffled against the faded chair.

"How do you feel—after you shoot someone?"

Hotch folded the lid of the pizza box closed, tucking the tabs carefully inside to preserve the four and a half uneaten pieces. Then he sank back down onto the edge of the couch and knotted his hands in his lap.

"That usually depends on why I had to shoot them." He wondered if Reid would notice the adjustment, had to, a justification of the lives he'd sometimes taken. The life Reid had been forced to take. "What the unsub's state of mind was, what his endgame was…whether I think I gave him what he wanted, whether there was another way out. And whether any lives were in the balance," he added, more softly. Reid dropped his gaze—not something he felt comfortable taking credit for, maybe. Hotch leaned forward and braced his elbows on his knees. "It's never an easy choice, but sometimes it's a necessary one. I believe you did the right thing today, and I know every person in that ER does, too."

"I know," Reid said. His eyes flickered up to Hotch's just briefly before he looked down at his lap once more. "But what about…after? I mean, what do you do when it's all over?"

Hotch sighed, recognizing all too well the way Reid's fingers were digging into the fabric of his armrest. "After…you work through it. You replay it a few times in your head, find all the places where you made the right move, the ways he didn't give you a choice. You go home, get a little sleep. Stay up late watching TV and eating pizza with a friend."

He cracked a small smile and watched Reid's lips quirk up in turn. He was not certain, suddenly, whether he had ever referred to Reid as a friend before, instead of a colleague—but he wanted to be, and he hoped Reid considered him the same. Reid was fiddling with a seam on the arm of the chair, and Hotch watched him for a moment before continuing.

"You learn from it, and then let yourself let it go. And Reid…" he started to add, but then paused; the name felt too formal, all of a sudden, for what he wanted to say. "Spencer," he tried again, a little uncertain in the syllables. Reid jerked his head up, surprise clear on his face, and Hotch faltered. "May I call you Spencer?" he asked, worried that he had crossed a line. But Reid only nodded, and though the motion was a little too fast Hotch thought it was eager, not uncomfortable. He reached out and set one hand carefully on the edge of the armchair, next to Reid's elbow. "You're not alone with this, Spencer. Jason an—" He stopped, then shook his head, choosing not to speak for Gideon. "I am always here for you if you want to talk. Or, you know…do your part regarding those 252 million pounds of pepperoni."

Reid swallowed hard, but he was smiling, too, just barely, the curve of his lips stark against skin even paler than usual in the TV light. Hotch patted the chair arm twice and stood up, taking the pizza box with him. He was almost to the edge of the kitchen when he heard Reid clear his throat.

"Thanks, Hotch."

Hotch turned around, making certain he caught Reid's gaze before he spoke. "Anytime," he said, and hoped Reid could tell how much he meant it. Then he leaned back against the doorframe, the pizza box balanced on one hip. "And it's a little different when we're in the office, but…there's nothing wrong with Aaron." Then he stepped into the kitchen and scraped their plates into the trash can, wondering absently why the surprise on Reid's face had made him smile.

He ended up spending the night on Reid's lumpy couch, and rose for work far too early the next morning with a stiff back and the aftertaste of pizza lingering in his dry mouth. But somehow that didn't seem as important as Reid offering him a cup of black coffee and a hesitant, fumbled Good morning…Aaron.

Perhaps there was no reason for Reid to take the bus quite so often.