He's not entirely surprised at the state of his bunk, though he wasn't exactly expecting it, so there's an element of that in it, an element of taking-a-moment-to-deal. To compose himself. Not surprised, because he might not be able to (seemingly) read minds as well as River can, but he can read people like he reads books, examine each word and how it fits with the others enough to make sense of it, understand it, quicker than others if not with greater depth. So it only takes a few moments once he's stepped into the bunk and the hasty chaos spread over the bed, an instant, really, before he understands what happened, and who the perpetrator was, and the automatic fist clenched around his stomach loosens almost before he realises why; a subconscious taking-stock of what's there (or more importantly, what isn't), shows nothing valuable is missing, or rather; nothing much at all. And huh, valuable. Still shaking a little from the sudden hammering-home of the fact that there's only really one thing still valuable to him in the 'verse (not these little shreds of things left that he had come to treasure so much), one person, so much so that the gust of heated air from Serenity abruptly hovering overhead was like a slap in the face that almost caused regret that he couldn't give his life for it any more.
And so he sits down abruptly on the bed, on an unoccupied edge, or at least an edge only occupied by one gauzy, purplish shirt whose texture he still remembers sliding through his hands as he stuffed the cases full of things he hadn't been sure he'd need in a moment where there was only one sure thing left.
Sentimentality, really. Moments he holds close to, clings to like the treasures and gadgets useless in the black; memories he's worn smooth with many tellings, some he doesn't like to get to know too well, some he's holding safe for River while her mind's open like floodgates, letting everything out, not letting anything back in.
"I read your diary." Jayne's in the still-open doorway, picking something out of his teeth. Food. A meal. Simon forgets how long since they got back on the ship, thinks that maybe some part of him decided to skip dinner in favour of regrouping on his own, here; while of course in the meantime another part has been perpetually aware of the relatively calm cadence of River's voice in the background, blended amidst the vibrating hum of the ship around them.
"I didn't know you could read," Jayne's eyes narrow a bit at that, and Simon almost (almost) feels guilty; defensive retorts from his side aren't always the most appropriate response to Jayne's always-blunt but only sometimes-crude attempts at interaction.
"Well I ain't never been to no special school," -- the emphasis is plain, sarcasm to the point -- "but book learnin' comes in handy when you got to make sure you're gettin' paid right. Or read a wanted poster." He leers a little. Simon shifts a little, tenses where he's still sitting on the bed as Jayne lifts a booted foot to stand entirely in the doorway. "'Sides," his tone changes from blunt and gruff to blunt and suggestive, and he hooks thumbs into belt loops, allowing the weight of his slouch to cant his hips forward. "Seems to me knowing my letters has truly come in handy at last. I didn't know you was sly."
It takes a moment, examining the word, running it through its possible meanings and how it fits into the jigsaw of Jayne's dialect until his brain catches up with the rapid acceleration of his heartbeat and he remembers some of the choice excerpts from the diary in question that could very well explain Jayne's behaviour, especially considering the way Jayne's metaphorical ears have been known to metaphorically prick up when, er, such talk arises. Not that Simon is as frank as all that even in his own journals, but Jayne has been known in the past to take up what might be left for some as mere suggestion. And -- the admission enough to stutter Simon's disobedient heart along bit faster for a few beats -- Jayne isn't stupid, as such.
And Jayne has stepped closer again, and the door to Simon's bunk is slid half-closed, and River's voice is still soft and easy but more distant now and Simon's hands half-curled and damp inside on his thighs until he flattens them, smoothes them down and over his knees, feeling a little grit from the dusty moon they just rose from rolling over the worn weave of the fabric. He looks up from the remaining scattering of his possessions over the bedspread, looks up into Jayne's face, realises he hasn't replied to Jayne's last statement, opens his mouth, stops.
Objects in space. Moments in time. He swallows down the words trying to creep out of him, finds his throat dry. Jayne's crowding him; one hand on his belt buckle, lined skin a little pale where it's usually hidden beneath the half-gloves, but clean; the other gripping Simon's shoulder, hot and calloused even through the silk vest and linen shirt.
"Doc," Jayne says, like he means it and nothing else, "you think too much."