Mud Freak

Missable, and a soft-hearted one: exhaust all of Mud's dialogue across the game. The snag is Mud is a weedy, cowardly little sort who dies at the drop of a hat - if he's killed, that's it, gone for the run. Look out for him whenever there's a scrap nearby, check back after big story beats, and keep chatting until he's out of lines. Keep a save from before anything that might get him killed.