9-1-1 head canon: Buck is actually hella traumatized from all the time he’s spent in and out of the hospital and regularly gets anxious being around the ambulance and Eddie is the only one ever allowed to check him over anymore bc husbands
given the amount of time this man has spent either in hospital or watching his loved ones suffer in hospital this is understandable
and it wouldn’t be a big thing either, he’d try to stifle the reaction because this is part of his job and he doesn’t want people to think that he can’t do it, but eddie notices (because eddie always notices)
and it isn’t mentioned, because eddie knows buck doesn’t want it voiced, so he just gives him wordless support with some lingering touches and supportive smiles (and if he sits a bit closer to him in the truck after a close medical call, that’s nobody’s business but their own)