The line is almost corny, but the way Bucky says is so genuine that Sam just pulls him in for another kiss, sweet and long. Is he going to stop being a brat to Bucky just cause he's being a good alpha? Absolutely not.

But Sam can admit that for all that Bucky vexes him, he's doing a good job being the caretaker and provider so few alphas actually want to be.

"Good boy," Sam murmurs against his lips. Somehow manages to pull away after one last peck to unlock the door and let them both in.