 Jack in particular finally learns how to forgive himself for a past sin- when he accidentally lost his younger brother Gray during an alien attack- when he is reunited with his brother.Driven mad by his long imprisonment, Gray buries Jack alive for over eighteen hundred years before Jack is rescued by Torchwood and put into cryopreservation in order to ensure that the timeline proceeds unchanged.Despite having spent hundreds of years buried alive, Jack's first actions upon awakening in the present and seeing Gray are to forgive Gray for what he has done to him.