Quote Originally Posted by bunsen_h View Post
Clearly it's a grammatical-mode thing. Other-god speaking to a mortal uses one form, god's own avatar speaking to other gods' avatars uses a different one.
In the real world it was also a grammatical (case) difference. Fenrir is nominative case, Fenris genitive, as part of the phrase Fenrisulfr, that is, Fenris Wolf.