Reincarnated Misfortune (3.5e Flaw)
From D&D Wiki
Things in this life remind you of things from your last, and these things make you sad.
Prerequisite: Must have been affected by Reincarnate, or some other means of reincarnation
Effect: From time to time, the character sees something that reminds him of his former lives. At the start of every encounter, there is a 25% chance that he notices something that causes him to recall his past. If this happens, he is dazed for 1 round and thereafter is shaken until the encounter is resolved.
Roleplaying Ideas: Your character may or may not know any details from their previous life. It is entirely possible that some strange stimulus could just trigger certain buried memories that causes a sudden rush of emotion or lack thereof, leaving the character dazed and listless amid an otherwise chaotic round of combat.