Hope this is the right place for this question, don't want to give anyway any spoilers.

Just did the part of the quest where you have to get everyone up on the mountain and negotiate a peace. After the yelling was over, one of the Blades tells me that they know who Paarthurnax is and where he's located, and that the Greybeards have been protecting him all this time.

She tells me to kill Paarthurnax.

The only response I have available to that statement is "Paarthurnax is dead." She's happy. The Greybeards aer not.

Last time I left Paarthurnax, he was at the Throat of the World, and very much alive. I never received a quest to kill him, never tried to kill him, either.

Ran all the way to the top of the mountain. He's not there. And I have to say, I'm a little bummed out; he was a cool dragon. I'd actually have a beer with the old guy.

Is this a glitch? Again, I never received a quest to kill him, and I was floored to hear that I had done him in. Just not sure if this was a bug somewhere.

Yeah, if you never got the quest to kill him before, he should be alive. AFAIK he's essential up until you get the order to kill him so how he could be dead already is a mystery. First time I've heard of this happening and I haven't found it listed anywhere at UESP either.

Damn Dawnguard Vampires.

Seriously though, this is weird - I've never heard of this bug either. Keep us updated.

It's certainly unusual: I usually get the opposite bug, where the game doesn't remove the "essential" flag.

Did he fall off the mountain?

He did in my game. It made the mainquest very annoying.

Hmmm, must be a bug, that is not supposed to happen.