Anybody else notice the new Sif cutscene? I just watched it on youtube and it shows him walking up to you and howling before he grabs his sword. It is almost like he remembers you saved him from the Abyss. Now its going to be twice as hard to kill the poor thing
PS: you have to have freed him for the new cutscene to work
PS: you have to have freed him for the new cutscene to work