Bucky should've checked. About that, about shifting, definitely. He and Sam should probably have actual conversations about how he feels about those things. He gives Sam a rueful smile, and a nod.

Advice heard.

Sam bolts. Bucky whoops and gives chase. Lets Sam escape his grasp a few times over the next ten, fifteen minutes.

Despite his cock bobbing enthusiastically at these shenanigans, he's careful not to get anything on Sam's clothes. Which might be half the reason Sam keeps slipping from his grasp.