What i was thinking about is a small part after the end of the mainquest where you (il try not to spoil too much for the people just looking inside) destroy the hearth.
What i was thinking about is that after you destroy it some man comes to you saying you made a big mistake. The hearth shouldn't be destroyed because it would mean the end of the world.
there will be some immortal beast chasing you every now and then, which you have to flee from, because he is immortal (duh).
The whole meaning is to rebuilt the hearth, get special items from strong monsters needed to rebuilt the hearth.
After rebuilding it the immortal monster finds you again, but because the hearth was rebuilt it is mortal now. You slay it, and voila, your done.
At the end you should get some reward that i havent thought of, maybe a weak version of the protection of that immortal beast.
Ofcourse this whole story is just an idea and i cant do any scripting or thing whatsoever, so if anyone finds this a nice idea and wants to make a mod out of it please post it here. I can't really help except for some ideas of what would happen in the story. Well, if your a modder, and interested, POST!