Long after he's otherwise recovered from being brutally tortured and raped by Hydra goons, Steve avoids physical intimacy. Not because he's afraid of reliving the ordeal, but because most of his moments of jumpiness have involved violently lashing out to defend himself. What scares him isn't the flashback itself, it's that he'll start struggling and seriously injure a more breakable partner.

So... it's almost a relief when his partner procures a set of heavy-duty wrist and ankle cuffs and offers to chain him down so they can finally have sex.

Give me sweet, hot, intensely kinky recovery sex, where on one level Steve finds the restraints calming/reassuring because they mean he can't hurt anyone else with his knee-jerk responses. But he's also constantly teetering on the edge of getting freaked out, because having sexual stuff done to him while he's immobilized is still an extremely loaded activity. The challenge, for both of them, becomes helping him keep his equilibrium and maintain a sense of control over the proceedings, even when he's physically barred from using his body to intervene.

+ The restraints are necessary, and he reflexively lashes out at least once
++ Steve giving orders and topping from the bottom
+++ Ordering his partner to touch him in the same places he was hurt, or even to fuck him, and enjoying it even if it gets him all tensed up