I really enjoy looking at Kiritsugu's past. It highlights some point on altruism,ethics and knowing one's self. Kiritsugu seems to conclude that a consequentialistic approach is the way to go. however, at the same time it causes him to do acts of monstrosities ,leading to his cold blooded killing personality. Choosing the path with least destruction ,but at the same time sacrificing his humanity for it. On the surface he may seem heartless , but if you take it from a mathematical point of view ,it's the better choice. Perhaps this might forshadow future events of the series like if he's forced into a situation where he has to kill his wife or daughter for the sake of the populous .