When Sebastian learned about the existence of Slytherin’s Scriptorium, he asked for your help, as well as Ominis’s, to gain access to the chamber. However, before entering it, the three of you encountered a door that required the use of the Cruciatus Curse to open. Sebastian was willing to cast or endure the curse if it meant uncovering the secrets hidden within, as he firmly believed they could be used to help his twin sister, Anne.

Ominis was reluctant throughout the entire journey and, once it was over, urged Sebastian to abandon his search. Sebastian did not.

With your help, Sebastian discovered Slytherin’s Spellbook inside the Scriptorium, a compendium written by Salazar Slytherin himself.

Days after reading and studying it, Sebastian learned of the existence of a relic, so once again he asked for your help and arranged to meet you in a cave. There, you fought spiders and found the notes of a medieval student that hinted at the existence of a dark relic capable of curing ailments. This only made Sebastian even more determined to uncover it, which he ultimately did. However, you soon realized that Ominis had followed you, and once again he urged Sebastian to stop meddling with the Dark Arts—but Sebastian continued regardless.

Shortly after leaving, you found Feldcroft devastated by Ranrok’s Loyalists. You and Sebastian fought several goblins before finding Anne wounded in a field outside her home. Anne was about to be killed by a goblin, so Sebastian used the Imperius Curse to force the goblin to take its own life.

Afterward, Sebastian tried to help Anne up from the ground, but she rejected his help. Solomon approached, shouting in anger and disappointment, and drove Sebastian out of his home, forbidding him from ever coming near them again. Sebastian was left devastated, furious, and ranting as you approached him.