An idea for a type of event.
As the conclusion of a storyline one of your hearthlings disappear. It might be as a consequence for failing the quest or it might be a heroic sacrifice where the hearthling saves the town by running in and bashing the magic crystal or stabbing the evil sorcerer. Ideally that hearthling should have played an important part in the events leading up to that point and afterwards you may be able to make a statue as a memory. It might even be a requirement for the storyline to happen that you have changed the name of the hearthling. Everything to make sure that you will miss that hearthling and remember it.
Some time later (a week, a month, maybe a lot more) in another one of your towns, maybe even in another biom, suddenly a hearthling appears and when you inspect it you’re chocked to realize that it’s you lost hero. Same name, same stats, same equipment, telling you that it saw a blinding light and then all of a sudden here it was.
If you want to give it a heroic entrance it might show up just as your town is about to be overrun by enemies.
Alternatively, if alternate planes, that was a stretch goal in the kickstarter, ever makes it into the game then it might tell you that it’s been living there all this time, that it just now found a way back and that it can show you how to get there. Or, when you go to an alternate plane you find the lost hearthling there. In these cases the hearthling should not have the exact same stats and equipment as when you last saw it. It might even have gone a bit insane from living alone in a strange world.
I think it would make for a good story and a nice surprise for the player, giving the player the feeling that things are more connected than they first thought.