Just like the dog that had bitten him in a past life was not evil, but still a combatant, it is likely that people you sense negatively about right away were your combatants in a previous life. Maybe.
I read also on a post somewhere here that there is a theory that a birth mark may actually be the entrance wound to whatever killed you in your past life. that would be interesting. I have a son that has a birthmark right below his heart. Must have been a soldier . . .