I've been curious if these two daedric princes share any alliance or rivalry with eachother. I ask because of the obvious similarities in their power over disease. Would Namira/Peryits shun a priest/acolyte/follower for serving the other as well as them?

Just curious between the relationship between these two gods and how they would handle (if they even would at all) sharing a priest/servant.

I can't imagine the Daedra Princes sharing any followers, much less actual priest(esse)s, regardless of which princes said follower worships. They strike me as being pretty jealous of their mortals.