The fast route
Mud is normally encountered around the Old Camp castle gate and his nearby hut. When you are ready to end the follower sequence:
- Make a manual save.
- Use the dialogue that tells Mud to leave.
- Fight him until he is knocked down.
- Do not execute him. Wait for him to stand and finish his response.
Independent editorial play notes and player reports agree that this is the intended way to stop the following behavior.
Mud Freak achievement route
The official achievement only says to exhaust all of Mud's dialogue. The commonly documented community breakdown is one introduction, nineteen wandering lines, two player-selected lines, and two lines tied to the knockout sequence. Treat the count as a checklist, not an official specification.
Before knocking him out, let him follow long enough to hear the wandering lines and select both Please... shut up and Piss off when they are available. Keep the save so you can continue listening if the achievement does not trigger.
If Mud keeps teleporting back
Reload the save before the knockout, repeat the final dialogue, and make sure he survives the fight. If he is still attached to the player state, move to a clean manual save rather than killing him and losing the achievement path permanently.