Board Thread:Lore Discussion/@comment-66.243.250.142-20150503041403/@comment-6881629-20150503092731

If you ask Arngeir about what happened and if you really killed Alduin he'll say -

"Perhaps, perhaps not. Dragons are not like normal mortal creatures, and Alduin is unique even among dragonkind. He may be permitted to return at the end of time to fulfill his destiny as the World-Eater. But that is for the Gods to decide. You have done your part."