2401 Penitent Tangent is (or was) the caretaker of Installation 05. In his spare time he would fly round and round a tree in the middle of a swamp, watching people fight over nothing in particular. This habit is known by doctors as the 'Backwash Syndrome'.
It is no wonder then that the Flood were able to escape from the containment facilities on the ring, since 2401 Penitent Tangent didn't even look after them. Since he was near to the Flood Containment Facilities (in the swamp) he was captured first.
2401 Penitent Tangent in the clutches of the Gravemind
He's insane, just like his buddy Guilty Guilty, and he was captured by a Gravemind which makes him even more insane. To be honest, no-one really knows how this happened, but he must have either neglected his duties or been co-erced by the Gravemind. He now sits under the Library of Installation 05 where the Gravemind used to sit, since old Gravy abandoned his two hostages when he left the ring. Now all Penitent Tangent does all day is have arguements with the Prophet of Regret.
A hologram of 2401 Penitent Tangent