There are a lot of things that everyone on Team Voltron accepts a posteriori. "Shiro doesn't sleep" is one of these things.
If Shiro's not already half-asleep to begin with, he won't even agree to go to bed — and even when he does retire to his room, he doesn't sleep for more than an hour or two. He would if he could, but he can't — not when he's tormented by nightmares that are all the more terrifying on account of the fact that they're memories, not just products of his subconscious mind. When he closes his eyes, Shiro sees exactly how he became what the Galra made him: the Champion, a living, breathing weapon that leaves no one alive and nothing behind. And if he doesn't wake up quick enough, he'll be forced to watch himself behead a fellow prisoner-of-war with the axe he'd been given at the start of the match, then, as he trudges back to the Galrans there to shepherd him back to his cell, step over the slaughtered gladiator's blood not out of respect for a fellow POW, but simply because the thin-soled shoes he had been issued after he'd been captured offered a bit of warmth, and he didn't want to get them wet. The temperature of the cells gladiators were kept in was only just above freezing, after all.
After Shiro does, at last, wake up — in a cold sweat in the middle of the night — he'll go shower, then come back to his room and do some basic exercises until he hears the faint sound of Hunk's alarm clock going off, at which point he'll go down to the kitchen and wait to help Hunk make breakfast (or, more accurately, keep Hunk company while he cooks breakfast, since Shiro can't even boil water). It'll be half a varga until Coran and Allura join them, and another half varga — at least — before the other paladins wander into the dining room. The first one to do so will be Keith, eager to get breakfast over with as quickly as possible so he can get some extra training in. The second one to stumble in will be Pidge, still dressed in her pajamas and looking more asleep than awake. The third and last one to arrive will be Lance, but he'll start chatting Hunk's ear off as soon as the Yellow Paladin sits down at the table.
While that's how most mornings go, there are days, however rare, that Shiro gets a good night's sleep — and when that happens, the usually light sleeper is harder to wake than a dead man. Shiro functions well on the insufficient amount of sleep he gets, but that doesn't mean that his body doesn't crave sleep, doesn't plead for sleep as loudly as the lungs of a drowning man scream for air.
When Shiro walks into the dining room feeling, for once, well-rested, he sees what he sees whenever he manages to get a good night's sleep and, consequently, sleeps in: Coran and Allura talking quietly amongst themselves, Keith and Lance arguing with each other, Hunk attempting to placate the both of them, and Pidge doing her best to ignore everyone.
"We should even have graduated from the Garrison by now!" Lance exclaims, popping the collar of his blue pajama shirt like it's the collar of the gray officer uniform Shiro had been stripped of when he was captured.
What did the Galra do with my uniform? the Black Paladin wonders as he takes a seat at the table.
"—except for you, Mullet," Lance continues haughtily as Shiro shoves the question out of his mind. Shiro gives Hunk an appreciative nod as the Yellow Paladin hands him a plate, then refocuses on Lance. "You know, what with you dropping out and all."
"I didn't drop out, you idiot. I was expelled!" Keith retorts, slamming his fists on the table. "And you should be grateful I was, because if I hadn't been, you'd still be a damned cargo pilot!" he adds, all but spitting out the word "cargo."
The reminder of why he had been promoted to fighter class makes Lance blanch, but before the Blue Paladin can respond, Shiro clears his throat. Loudly.
The antagonistic paladins, now aware of Shiro's presence, turn towards him. Shiro looks pointedly at both before simply saying "stow it, cadets" and turning back to his breakfast.
The two fall silent, but not for long — after just over a minute, Lance mutters under his breath, "what'd you even do to get kicked out? All Iverson ever said was that you had 'discipline issues.'"
The corner of Keith's mouth curls upwards into a snarl, but he answers with a collected, steadfast voice. "Nothing I wouldn't do a thousand times over again."
"I still can't believe you got booted from the Garrison," Shiro admits, swallowing a bite of Hunk's masterpiece and turning to look at Keith. "Didn't I tell you not to do anything stupid while I was gone?"
"You were gone for over a year, Shiro!" Keith defends. "They said you were dead!"
"My absence wasn't exactly entirely voluntary, Keith," Shiro deadpans.
"What'd you expect, Shiro?" Lance interjects, smirking. "Keith can't refrain from doing something stupid for five minutes, never mind an entire year."
"Lance," Shiro says warningly. "That's enough."
"You can't tell me what to do," Lance grumbles, crossing his arms over his chest. "You aren't my father."
"No, I'm not, but—."
"—he might as well be," Pidge interrupts, causing everyone at the table to turn towards her. "He's older than everyone here except Coran, and Allura, too, I guess, if you count the ten thousand years she spent in stasis," she continues. "He's even got white hair!"
Shiro crosses his eyes to look at the white bangs spilling onto his forehead, and before he can stop it, a blush spreads across his cheeks.
"He's not our dad," Keith grumbles, crossing his arms over his chest and shooting Pidge a leveling glare. "And just for the record," he adds, turning towards Lance, "your comebacks are about as good as your shitty piloting skills."
"Keith!" Shiro admonishes.
"What?" Keith hisses, whipping his head around to look at Shiro. "Lance started it!"
"I don't care who started it," Shiro huffs. I swear these paladins act more like toddlers than teenagers, sometimes! "I'm asking you to end it. You need to stop letting Lance get a rise out of you. This temper of yours is probably what got you booted from the Garrison! You were a brilliant pilot, Keith. You beat my records! You could've—."
"Yeah, I could have let the Garrison administration piss all over your proverbial grave," Keith growls, "but I wasn't going to let those assholes propagate that stupid fucking lie about the Kerberos mission failing because of—."
"Okay, wait a second, Keith. Did Shiro just say you beat his records?" Pidge interrupts.
"Yeah…?"
"Whoa," she breathes. "Shiro's records were legendary!"
"Shiro's records were stale," Keith corrects. He turns toward Shiro, a complacent smirk on his face. "I entered the Garrison five years after you graduated, and your simulator scores were still records. Someone had to knock you off your pedestal."
"You graduated eight years ago, Shiro?" Hunk interjects before Shiro can respond.
"… yes," Shiro admits reluctantly.
"Quiznak."
It's not hard to translate that: "Shit, dude, you're old."
Yeah, Shiro thinks as he looks around at the other paladins. Yeah, I really am.
It wasn't, in reality, that long ago that Shiro and Matt Holt were celebrating their having been selected for the Kerberos mission, and Shiro was joking about being able to lure aliens back to Earth to be studied by Commander Holt and other Garrison scientists with tales of Japanese cherry blossoms, spaghetti, and the wondrous Antelope Canyon, Arizona… but it might as well have been eons ago.
I was so naïve…
"Shiro?"
"Shiro!"
"Hmm?" Shiro murmurs, turning in his head in the direction of the voices he had barely registered.
"What time do you want everyone on the training deck?" Keith asks.
"Oh, uh… be there in fifteen minutes," he stammers.
The three youngest paladins disperse to go put on their armor, but Keith stays put. "You alright, Shiro?" he asks, one eyebrow raised in concern.
"Yeah. Yeah, I'm fine, Keith," Shiro answers a bit too quickly. Damn. "I'm sorry. I just spaced out for a minute."
"… okay," Keith decides. "I'm here if you need to talk, though," he adds before leaving the room, leaving Shiro alone.
Shiro waits until he can't hear Keith's footsteps anymore, then bends down to retrieve his helmet from where he'd set it on the floor next to his chair. He tucks it underneath his cybernetic arm, then places his still virtually-untouched plate in the Altean equivalent of a dishwasher and starts the trip to the training deck, all too aware of the snow-white bangs that flutter whenever he walks past an air vent.