In Dragon Age 2, there are several optional party members that can join you throughout the game.
Fenris is a warrior and does not join your party automatically during the main story line.
Fenris is available in Act 1 in Holding Caves. He will join your party temporarily, and heading from Kirkwall toward Soundermount with Fenris in your party should activate a group of Slavers ambushing you for a quest called A Bitter Pill. You’ll go through a bunch of dialogue, and ultimately fight off a bunch of slavers until you fight a lady named Hadriana. Once you defeat her, Fenris will join your party.
Fenris will clash with any caster in your party, including Hawke if you chose a mage type for him.
