Sebastian will only show up if you've convinced Edward Willoughsby to discuss the "personal measures" he's taking in the Boil with you. He will join your party if you accept and complete his quest to kill one or both of the gang leaders in the Boil, and then confide in him your story. Sebastian has a plethora of tech gear, so you might want to add him long enough to acquire them from him.
- Location: Tarant, The Boil
- Initial level: 30