It takes everything in Bucky's power to not simply put his fist into the wall. The question's open-ended, undirected, and he's not sure how much he's about to be forced to tell; he's not inclined to stick around and find out.

"Because there's some kind of %*!#ed up island thing going around today," he says through gritted teeth, trying to bite his tongue. The conflict is clear on his face. "And I pointblank refuse to add spilling my guts to you to the list of things I've been compelled to do against my will."