I've just bumped into my old drinking buddy while on a quest.
I didn't recognize (or even see) him at first.
It was on a Companions heirloom quest in Morvunskar. I'd been doing the usual sneak attacks with the bow to worm my way into the place when I heard blasts of destructive magic coming from up ahead. Fearing discovery I went all the more carefully and the last hall contained four mages fighting somebody who was hidden from my view. I took out the first two and then moved to the lower level where I saw an arch-mage backed up against a wall, furiously launching inferno attacks against a Daedric clad warrior who appeared to have real horns sprouting from his head rather than just wearing a horned helmet.
This warrior was also being blasted from the side but seemed to take no damage. I helped him out with the first fire mage and then the second. I approached the unknown warrior gingerly, in case he decided to fight me. When he turned to face me, his face was streaked with red and he casually strolled past. He really did have horns. He was tall, too.
Clicking on the figure to speak, the name Sanguine came up. It took a while to remember that he was the Daedric prince from a quest called something like 'a night to remember'*, the one who got me drunk in Whiterun.
I backed away when he wouldn't speak and he just wandered about the hall. When I was far enough away to think I could leg it if things turned sour, I fired an arrow at him but it passed clean through and he paid no attention. Maybe that's just as well.
Have any of you met Sanguine randomly like that, or any other Daedric prince for that matter?
* ironic that I can't remember if that's the right name