Shared wet dreams! Maybe it's due to a new bond that only one or none of them know about, or a weird interaction with some alien fauna/flora/geological or space phenomenon but!! Pining, god awful, awkward interactions that have them wondering if it's actually awkward or if waking from those dreams just skewed their perspectives.
Or maybe these dreams are not out of the ordinary for kirk. He has lived so many months/ years of aching from imagined tender loving that he doesn't register the change. Much. Is it just him or has spock been avoiding eye contact these past few days?
Maybe it's not the content of the dreams that are out of the ordinary for spock but the increased frequency. With how in-tune Vulcans are with their mental landscapes he probably figures out somethings up pretty quickly.
Does this happen when they have accepted their feelings? Embraced their feelings but suppressed them? For what reasons? Are they aware their regard is knowingly or unknowingly returned? Or are they 20000 leagues deep in denial? Is it one or both of them?
+ Also vulcan culture!! Are wet dreams and/or the unintended bond considered a natural biological process or a grevious lack of control? How much influence will this have on spock's actions? How comfortable is he with his human half? Has he found a way to reconcile it w/ the Vulcan way? Any unknown biases? Does JIM have any biases he is blind to on account of spock being vulcan(like maybe heteronormativity b/c pon farr (or if aos, repopulation efforts/only seen spock with uhura) or assuming that vulcans are prudes, no love matches, e.t.c)?
I'm always a huge fan of sleep telepathy. This sounds like an awesome idea