Erritis will start acting weird once you enter the Valley of Dead Heroes. Talk to him to learn that he is terrified of visting one of the nearby graves. Visit the Glowing Alcove (M12.7) and take the shepherd's stick. A strange scene will play out, telling you that the Calm received a new reflection.
The Calm received a new reflection - Erritis. Visit the location and talk to the man to learn the sad truth about the hero. As it turns out, he is possessed by demons that force him to do heroic deeds. He will ask for your help in finding someone that will be able to help him.
Travel to Bloom to continue the task. Visit The Old Slave Block and talk with Skoura (M17.3) about Erritis' problem. During her examination, the woman will take a sample of his aura. You'll learn that you need to return to the Calm and talk with Erritis' reflection.
Enter the Calm and talk to Erritis' reflection. Begin a dialogue with the demons that had corrupted him. The dialogue enables you to decide on Erittis' future:
- You can agree to a pact with the demons that will strengthen Erritis (+1 to Might and Speed, but drain his vital strength in progress, leading to a faster death. However, an revitalized Erritis will stay in your party and continue to support you. The quest will end, netting you 40 Experience Points.
- If you will press the demons to leave Erritis' body, they will agree to a deal - the demons will stop pushing him to do heroic deeds, but will stay in his body forever. The man won't receive a bonus to his statistics, while the party will receive 40 Experience Points.
The event will influence the final quest - The Right to Exist. The quest will see you encounter Erritis in the Calm. You can use the opportunity to sever the man from the demons (you'll acquire 100 Experience Points). Erritis will disappear, and you won't be able to add him to your party. However, this will enable Erritis to rest peacefully.