Gonna get a little nff here and say I think we need more Thunderbolts content about how the supersoldier serum just makes people insatiably horny all the time.
Especially with John because he's so new to it and his body is still learning how to handle it and he hasn't felt this since he was a damn teenager and it's embarrassing?? Like, Bob brushes past him in the kitchen one morning and he smells his shampoo and gets an instant hard-on. He catches Ava making some alterations to her suit so it's pulled down around her waist and he gets lightheaded from seeing her bare shoulders. Bucky stares at him too long and he has to take a cold shower.
Ya know???
But also, Bucky feels it too, he's just had so much more time to handle it. It's sad when you think about it really but when he was The Winter Soldier that wasn't even an issue (unless you subscribe to the theory he was used for things other than assassinations but that's wholly different too) and then afterwards he's barely had time to even breathe let alone think about sex. It maybe catches up to him post-Wakanda/deprogramming and after TFATWS and hits him like a truck which would be kinda fun to examine too.
And lbr Alexei doesn't even try to hide it or manage it, he's unapologetically horny and it's absolutely mortifying to Yelena.