I've beaten the MQ, and I was wondering because I was hanging out up there today, and the whole time (I walked from High Hrothgar to the peak & Paarthurnax) a blood dragon was circling around. It never attacked me, but it did attack some ice wraiths after I had walked on a bit.
Does anyone know if they can? Will they get their asses kicked by the Greybeards or Paarthurnax?
Edit: meant to post in the spoiler forum, sorry.