I completed Sanguine's quest (when you drink with Sam and appear in Markart). Much later I returned to Morvunskar, the ruins that lead to the misty grove portal where Sam is originally with the staff. This time though, Sanguine was in the ruin (outside the portal) killing mages. He didn't want to talk to me, kept saying "want something?" so I entered the portal just to see if something's changed.

Well, nothing's changed and now I can't return to the ruins because there's no portal back. When you're doing the quest, you're taken back automatically after the dialog's over. Now I'm trapped there, am I missing something?

I'm going to load a previous save but watch out, dont't enter the portal if you haven't saved for a while...