The way that Steve in inhaling that scent, it probably would surprise him to know that Bucky didn't wear aftershave or cologne any more. It was trained out of him when he started going on covert ops overseas and working as a sniper, it was no good if the enemy caught a whiff of something perfumed on the breeze to give you away. So all that Steve was smelling was Bucky's own scent.

Penny was struggling, because Steve looked human and Bucky had said he was a friend, but he smelled like an alpha and a dangerous one. Like a rabid dog, or a wolf, and that instinct said to fight and protect. In the end she decided she'd tolerate his presence but be watchful.

Bucky is fairly sure that Steve won't discover his illegal guns, he's the sort of person to not go snooping when he's been careful of Bucky's boundaries so far - the last day or so of oddness notwithstanding - but he's still down to the corner shop and back in record time, running so as not to give himself time to panic.

"Steve?"

He nearly falls over Penny at the door, craning his neck to look for his potentially swollen friend.