Muriel unknowingly lead Malachi to Castiel. At Malachi's place, both Malachi and Theo tortured Muriel and Castiel. On Malachi's orders, Theo killed Muriel. Malachi orders him to find out more information from Castiel. Once Malachi was gone, Theo switched sides and offered to work for Metatron, because Malachi was insane. He asks Castiel to use his "influence" over Metatron. Castiel got him to remove his handcuffs and in an instant sliced Theo's throat open with the angel blade. Theo's grace was taken in by Castiel, becoming an angel again. Now a human, Theo and his vessel were smote by Castiel.