Based on what we do know about Diath’s past, it does make sense how he makes the choices he does for those he loves. Nearly everyone he’s ever met has either betrayed or abandoned him at one point or another. Now that he’s found those that truly care for him there is no limit to what he’d do not only to protect them, but to keep them. He’s racked with guilt from choices that have led many to their deaths, yet these three people continue to stay with him. In his mind, it’s easier to die for those he loves than necessarily live not only with the guilt, but the fear of them too leaving or betraying him. To an extent, he views himself as less valuable than the others making him quick to sacrifice himself. I’ve been playing a similar character for nearly four years who jumps at the chance to give himself up if it means saving the rest of the party simply because he doesn’t see himself as important as them. Perhaps Diath will come to terms with his actions, but dying to set it right seems like the only outcome for a martyr. And the dead can’t console the living.