Speak to Fenris Head to Fenris' Mansion and talk to him to find out he found his sister and would like your help. Agree to start the quest 'Alone' .
Alone Head to The Hanged Man during the day to start a confrontation with Danarius.
Defeat the Slavers that continue to pour into the Hanged Man until Shades and a Rage Demon are summoned. Once they are defeated Corpses and Skeleton Archers come and Danarius becomes attackable. Focus on Danarius because when he dies the battle ends. The choices you make about Varianna effect Friendship and Rivalry. After the quest you receive the Curaiss of the Centurion and a codex update for The Centurion's Curaiss .