The Indelible Past (拭えぬ過去, Nugue nu Kako) is the ninth episode of the Second Season of Mobile Suit Gundam 00.
Setsuna and Tieria are confronted by Ali al-Saachez and his new Arche Gundam. A furious Tieria tries to avenge Lockon, but is overwhelmed by the enemy's fighting strength. From Tieria's behavior, Lyle learns that al-Saachez is the man who killed his brother.