It had every potential to be a perfect day, when it began.

Castiel was between hunts, and his last one had gone well, a restless spirit case in which no one had died and the interaction with the reaper he'd summoned had at least been civil, if not pleasant. He was back at the Men of Letters bunker, where he quietly enjoyed having his own room and access to Netflix. Sam and Dean were both here. There was no world-ending catastrophe immediately on the horizon.

And it was Thursday. That was always good.

Castiel was sitting at the map table, the one that had once lit up like a newborn galaxy with his falling brethren, with Sam. It was morning, so Sam was drinking coffee. Castiel could smell the skim milk and agave nectar in it. The two of them were silent, comfortably so. If there was one thing Castiel had learned over the better part of the last decade, it was that there was always a sort of magic to be found in the small moments, like this one. They were where the bonds that saved lives and worlds were built.

Sam tapped at his laptop with one hand, brows drawn characteristically together. Castiel watched the dance of his fingers on the trackpad. Dean came in then, carrying a plate of bacon and coffee of his own. Black, strong. There was a splash of whiskey in it that Castiel had not and would never tell Sam about. He kept their secrets for them, these days.

Dean set his mug down on the table, then touched Sam's hair where the dark waves fell around his neck. "Getting kinda long, doncha think?"

Sam looked up at him, cheek bulging where he was poking his tongue into the side of it.

"Gonna start getting in your eyes soon," Dean pointed out. "Only other option's to put it in a ponytail. Or a man-bun."

Sam sighed theatrically. "Fine. Guess I'll...dig out the scissors later. And the clippers."

"Why?"

From the way the Winchesters looked at Castiel when he spoke up, he was almost positive they'd forgotten he was there.

"Well, he needs a haircut," Dean said matter-of-factly, sitting down and grabbing a strip of bacon. He offered the plate to Castiel, who shook his head. He had no desire to taste all the separate molecular components of a pig.

"You cut his hair?" Castiel asked. He knew human hair grew, of course. It'd annoyed him to no end after he lost his Grace.

Sam cleared his throat. "We've been cutting each other's hair for years." He seemed mildly embarrassed. "Since Dean was in middle school. It's just...easier. Cheaper, definitely. And...I know what he likes his hair to look like, and vice versa."

Castiel frowned. He supposed it made sense, from a purely economic standpoint, and if one happened to consider Sam and Dean's relationshi -

Oh. Oh. His thoughts literally cut off mid-word, cleaved in half by a revelation so obvious it was almost painful. If it had been a Leviathan, it would have bitten him. Embarrassed, Castiel dropped his eyes to the table.

"Right. Of course you do."

"What d'you mean by that?" Dean's voice, muffled by a full mouth, was nonchalant, but Castiel read a warning in it.

"It makes sense," Castiel mumbled, growing uncomfortable.

"Yeah?" Dean bit into another strip of bacon with a loud crunch. "Why?"

"It doesn't matter. Never mind." Castiel frequently missed his wings at times like this, when he would have given anything to be able to escape with a single flap. He swallowed. "Sam? Have you found anything you'd like me to look into?" He nodded to his laptop.

"Uh, not really, but. What is it?" Sam was curious. "Why does it make sense we cut each other's hair? Tell us."

"You're..." With two sets of eyes weighing heavy on him, one green and the other currently a warm brown, Castiel faltered. "...mates."

There was silence for a long moment. Castiel went back to looking down at the table.

"Oh, we are, are we?" Dean asked. Castiel couldn't tell if he was angry or amused. His empathetic abilities had been lacking since the damage to his Grace.

"Why d'you say that?" Sam's eyebrows, which had come apart when Dean appeared, were back together now.

"I don't know." Castiel shrugged. "Your behavior, I suppose? All the things mates do."

"What do mates do?" They were both still sitting, still nursing their coffees. Dean was still eating. All those had to be good signs.

"I've only ever seen it with angels," Castiel began reluctantly. Talking about it in terms of his kind made it a little easier. "See...for us...plumage is highly important." He couldn't express exactly how important in English, and the Winchesters didn't speak enough Enochian to understand. "That was part of the reason it was so traumatic when we fell, and lost our wings. It's a massive breach of etiquette, bordering on criminal, to touch another angel's feathers, even in battle. We don't even use the wings in torture or interrogation. The one exception was Lucifer, whose crimes were determined to be so great the ordinary rules no longer applied to him." Sam cocked his head, frowning, and Castiel could tell he was curious. Perhaps they could talk more later. After they'd all forgotten about this particular conversation. "And, of course, mates may touch and preen each other's plumage. They preen frequently, often for comfort, occasionally preceding and following..."

Castiel trailed off. Fortunately enough for him, Dean was no longer paying attention, instead touching Sam's hair again. He had a silky handful of it, examining carefully the lightened tips.

"Pretty sure you got some split ends," Dean observed. Sam instantly turned to face him, whipping his hair out of his brother's hand.

"Seriously?!"

Dean shrugged, and Sam brought a length of hair in front of his eyes to stare hard at it. A few moments passed before they both seemed to realize Castiel had stopped talking.

"Look, Cas," Dean started, leaning back in his seat, "appreciate the birds and bees talk, but...not sure you noticed, but we're not angels. And that - " He gestured to Sam's hair. " - ain't a pair of wings. It's just not like that for us."

"I understand," Castiel said quietly.

That seemed to satisfy Dean. He turned his attention to Sam's hair once again, stroking and fondling. Sam leaned into the touch, slowly, just barely. Castiel watched his eyes fall blissfully closed when Dean added his other hand after wiping it clean on his jeans.

"Better not get bacon grease in my hair," Sam mumbled.

"Never heard of washing it?" Dean spread Sam's hair with gentle movements of his thumbs, peering at his roots.

"What is it?"

"How the fuck'm I goin' gray already, I mean, just about - " Dean was careful to put a lot of emphasis on that last part. " - and you've got more color than ever? Looks like a damn Clairol commercial in here."

Sam chuckled softly. Dean went back to his bacon, but kept one hand on Sam's hair. He traced over the curls and feathering of it with the pads of his fingers, callused and scarred.

"Gonna trim it, probably," Dean said around another strip of bacon. "Unless you want something different?" Sam shook his head, nearly imperceptible. "Yeah, didn't think so. I'll make it a little neater around your ears and neck, get it outta your face." Dean tucked an amber-and-chocolate strand behind Sam's ear. "Then maybe you can do me. Could use a cleanup."

Sam's eyes were still closed, his coffee and laptop forgotten. He kept moving his head in tiny increments to press his scalp to Dean's active fingers, and his face was peaceful, content. Small, soft, very human noises of gentle pleasure stirred in his throat and chest, involuntary, so quiet Dean probably couldn't hear them.

Castiel watched them, and had much the same feeling he'd had when he'd stumbled upon Michael and Lucifer preening, back when the world was new. Intimacy no one else was meant to witness, that he violated merely with his presence.

He violated it further, opening his mouth and asking an uncertain question he immediately regretted.

"Could I try cutting your hair?"

Sam's eyes opened and Dean looked up from his plate. Their emotional reactions, instantaneous, identical, and very negative, were more or less what Castiel had expected. They spoke at the same time.

"I don't think so."

"Uh...yeah. I'm not. Really sure that's a good idea."

"Could I watch, then?" Castiel asked them quietly.

Dean shrugged. "Sure. Weirdo." He took a loud slurp of his coffee, grimacing at the bite for just a second. His hand came off Sam to do it. "Hands above your waist, though. This ain't a damn peepshow."

Sam gave him an unimpressed look, his exasperation as pure as it was familiar.

"What?" Dean asked him. A beat of silence passed, the brothers staring each other down, and then Dean glanced at Castiel and offered a grudging "Sorry."

"Thank you."

Castiel was here in the bunker, with the Winchesters. He had his own room, his own Netflix account, his own car. He was a hunter, supported by two men to whom he was closer to now than he'd ever been to any of the angels he'd known since the Beginning. And yet he was so lonely he felt it as a physical pain in his tattered Grace, and in the phantom shapes of his missing wings. It was an old wound. Perhaps he'd carried it his entire life, with how familiar to him the hurt was. He didn't even know how he recognized it, if he'd never been without it.

He watched Sam and Dean, though. He watched both of them touch each other, combing each other's hair with their fingers, feeling length and shape and warmth. They were no more free of pain than he was, but there was something there besides their shared wounds. And it was enough just to see it.

For now.