I was at the College of Winterhold and an ancient dragon appeared. I tried to fight him but he wouldn't land, so I summoned Odaviing on him. After a while I suddenly absorbed a dragon soul. What happened? The ancient dragon was still flying, so I figure it must have been Odaviing. Skyrim Wiki says he can't die, but now I'm doubting it.
I tried reloading and not summoning Odaviing this time, and I still absorbed a dragon soul. What's going on?