The glitch was when I was in Solstheim, looking for gods-know-what which brought me to the only word wall on the island. Welp, the draugr I had cleaned off beforehand, but a blood dragon was there waiting for me. Not having any time for his shenanigans, I use Dragonrend and wait for him to crash down so I could stab him in the face. What does he do? Disintegrates mid-air!
Poor bastard keeps roaring as his flesh and soul burns away and eventually his skeleton crash-lands in front of me as I gain one dragon soul. So, this wasn’t the case of a respawned dragon as I got the soul, but seems that my Dragonrend had a bit more of a kick than usually.
Then, for the story:
I was in the place in the Reach where the weird dude does weird stuff to the spiders, Harmugstahl, if I recall correctly. I was to retrieve a Totem of Hircine from there with Aela. In the final room, where the weird dudemage talks to himself, I sneaky beaky forward and grab my bow, taking aim. Just as I release the trigger, what does Aela?