OP is the sort of person who admits to not understanding the difference between synonym and a relation (I assume they have nightmares about group theory), but the reveal of not blaming Karlach for anything Astarion did during his youth... Is hilarious. They were both grooming victims, respectively considered children by their culture when getting involved with the underworld. Astarion may even be mentally arrested at teenagehood because of his vampirism. That would turn another light on his highly selfish tendencies. That's not an age group with a fully developed prefrontal cortex. Though, I'm not sure the game means to imply this last part. It's very insistent that it comes from his personal philosophy. It's just another layer next to the questionable presence of innate alignment, capable of distorting thinking processes.