As DM, I would like an NPC to only show up occasionally for a short time (less than a day), then be required to leave without the PCs being able to follow. Is there a mechanic that would allow this?
The party cleric's backstory has her hubby disappearing during an adventure. I want him to show up every so often but not be able to stay. My thought is that their bond was strong enough to allow him to interact with her, but only for short periods. I want him to be able to explain why he must leave, which is why I want to know if there is something in the rules that would cause/allow that.