Tootling along to my noble quest,
when a Dragon appears and ruins my jest.
It circles overhead through wind and storm,
Though I'm ready with my bow, and fireball warm.
When I notice, with start,
a second red dot, and out leaps, a little fart.
I run into the trees with a worried waddle,
I look up to find it must have been twaddle.
No sign of enemy or second Dragon,
nought but my horse and burnt old wagon.
I shrug and turn to face the beast,
tracking with my bow, he hath not ceased.
As he dives overhead breathing fire and dread.
A clap of thunder and all 'a sudden he's dead.
So WTF?
In case my excellent poetry was too advanced for you, here's what happened. I encountered a dragon, thought I saw a second, distant (faded) red dot on the compass, It moved quickly so I thought two dragons. I couldn't see it in the sky so I then assumed it was a wolf or something.
I focused back on the dragon and as it swooped over it came close to the trees, I was under the trees so i couldn't get a good look, but there was some thunder, and it just dropped dead in front of me.
What happened? There was no one else around, maybe a farmer in the house I passed not too long back, but certainly nobody of that kind of power. The dragon definitely had full health too as I got a look when it first came by. Could it have been lightning? Can that even happen? Could the second faint dot I saw have been a second dragon that killed it? Do they fight at all? I don't think it was a dead dragon glitch as I consumed the soul.
For the record, my epic bow skills couldn't land either of the shots I got off, so it certainly wasn't me.
Update
Did you ever see it's health go down or did it just fall over dead. And where on the map are you? I've seen dragons fly by high level undead areas before and get themselves killed.
Nope, full health, then lost sight for about 10 seconds through the trees, then dead. There was a full screaming death throes animation, fall over and soul consuming.
This was not far from the back of Fort Amol, as that's where I was headed for a quest. I didn't see anything else while I was there, in terms of high level creatures, and it was dead directly in front of me so they must have been fairly close.
Update 2
OK after a short play tonight I've figured that the distant, faint red dot must have been story specific
Alduin
As I've just seen it on the compass again but could confirm by sight this time too. So that's that one solved. But do they fight at all? Could he be the one that killed the original dragon? Even accidentally?
Best Answer
I did some looking and there appear to be a good variety of glitches in which dragons can die. Some of them might fit your scenario:
Dragon flies (glitches) into ground and dies. Thunder sound, death throes animation, dead. No soul absorbed but this guy was pretty far away and never engaged the dragon:
There are a few recorded accounts of dragons dying when they land. This one shows a dragon that was at full HP who lands, dies, and the soul is still absorbed:
Same case as before, but the dragon was damaged:
There are plenty of other videos in which dragons die as the result of glitches, but I think that these three best match your scenario out of all of them. Let me know if this helps!
Here is an example of a dragon simply spawning dead in front of a player; the "dead dragon glitch" you mentioned earlier. This one doesn't match your scenario too well, but appears to be fairly common:
For the sake of showing that it appears to be possible, here's a video showing two dragons going at it (uhh... fighting):