Based on his appearance (mainly the similarity between his mask and Miraak's), I'm going to assume that he worships the new Dragonborn, our adversary.
I was wondering, do you think that after we defeat the antagonist, that we will inherit his worshipers and become the leader of the cult?
Perhaps afterwards we get Miraak's temple and it becomes a new house/palace filled with people who worship the almighty Dovahkiin!