My headcanon is Angel Bunny is Starswirl, and despite his best efforts cannot reverse the spell that made him a rabbit. He gave up a long time ago and just hangs out with whomever will tolerate him (he's canonically a jerk). Discord knows and won't change him back.
Cute! Though now I'm trying to remember any interactions he might've had with Twilight or Celestia, since they're about the only other ones who'd have a chance at reverting him.
OK, a quick silly one of mine. After
this scene my immediate thought was
this.