You get Fenris in a side mission, that I had honestly forgotten the name of till I looked it up. It had a pre-req quest. I'll link you to the quest you get Fenris in but not his wiki entry in case you don't want to be spoiled.

Bait and Switch; where you find the pissy elf named Fenris~


I had to look up some stuff for the game but I know if you read your mail a lot that helps. And just exploring.