Angel looks up from his perch behind the front corner as he marks his place in his book with one finger, not having caught a glimpse of who might have been waiting on the other side, but the scent of someone human and the fact that Dipper clearly isn't happy about whoever he saw are impossible to deny.

"Who is it?" He arches a single brow, questioning. "Not really in the habit of slamming doors around here."

Breaking them down with an unnecessarily dramatic kick, sure, but slamming seemed like a bit much.