tos mcspirk pre-relationship - thinking about mccoy having to beam down to go help save kirk's life, and he's informed right before he leaves that the planet kirk's currently bleeding out on (that is only allowing one doctor to beam down to) doesn't allow any adornments, so right before mccoy steps onto the transporter pad he takes his ring off (for the first time spock's ever seen) and he grabs spock's hand, and slides it onto his finger, and says, "hold onto this for me, will you?"
and spock doesn't generally fidget, but the entire time mccoy and kirk are gone he finds his fingers returning to the ring, and spinning it around his finger, and it's almost like a talisman, because mccoy never takes it off, so it's almost like it's a part of mccoy, and as long as spock can touch it then mccoy must be all right, and if mccoy is all right then spock knows - knows - that the good doctor will keep kirk alive, too.
and eventually the original landing party + bonus mccoy beam back up, and mccoy rushes kirk into surgery, and spock stays on the bridge handling the diplomatic fallout, twisting the ring around his finger again and again and again
and it's not until mccoy calls spock down to sickbay in time to see kirk's eyes slowly blink back open, alive and safe and out of danger, that spock realizes that mccoy still hasn't asked for the ring back. it's not, in fact, until kirk's eyes almost immediately are drawn to the ring, his eyebrows slightly raised, that spock realizes at all.
spock's finger feels surprisingly bare when he tugs the ring off - the metal warm from his skin - and presses it into the palm of mccoy's hand.
"thanks for keeping it safe," mccoy says, folding his fingers around it, his fingertips brushing spock's fingertips as spock slowly pulls his hand away.
spock raises an eyebrow, tilts his head towards the captain.
"i was about to say the same," he says.
"something you two want to tell me?" kirk asks, reaching out and tapping mccoy's fist, and the moment kirk touches it, mccoy's hand falls back open, like a flower uncurling.
"no rings planetside," mccoy says easily.
kirk's eyes are dark as he looks at him.
"you look naked without it," kirk says, his hand closing around mccoy's hand, ring and all, and tugging him a step closer to the hospital bed. "mind if i do the honors?"
and it's not until spock's gaze is locked on kirk's fingers deftly sliding the ring back where it belongs that spock finally understands the tightness that's been inhabiting his chest, this tightness that's been suffocating his lungs.
"looks good, doesn't it, spock?" kirk asks, something knowing in his eyes.
spock could stop himself from reaching out, if he wanted. he could stop himself from touching the ring, touching the hand, touching kirk's hand, too, where it's still holding mccoy's. he could stop himself, if he wanted.
he finds, as is so often the case with these two men, that he doesn't want to stop himself.
this time, he doesn't even try.