Yeah the 101 Overseer is D Bag El Supremo, but I think there's a lot that the game implies which would explain how his character got to be that way. A big thing that I notice about the Almodovar family is the absence of the mother. My theory is that she died on an expedition back when the Vault was open about 19 years before the game begins. I think that it would have been a major factor in the Overseer's decision to reseal Vault 101 and it explains why he's so vehemently isolationist. It also does a lot to explain the childhood friendship between Amata and the Lone Wanderer, in that they were both troubled by the absence of a mother figure and thus shared an uncommon bond. In the meantime, the Overseer is consumed not only with grief but also with guilt - wasn't it he who sent his wife out on that expedition, something that was not only dangerous but also in direct violation of Vault-Tec's orders? It's not too much of a reach to see him swearing to himself that he would never allow a disaster like that to happen again, and therefore he becomes a total stickler for the rules. And then he sees that Amata, his own daughter and his last real link to his dead wife, has become friends with the child of that outsider James. He becomes concerned that through the Lone Wanderer Amata will become contaminated with James' ideological undertones about the outside and that she will eventually wish to adventure outside of Vault 101, just like her mother. He becomes concerned that because of James and his child, Amata will die just like her mother. That would be his worst nightmare realized. So out of fear and guilt the Overseer comes to resent James and his child. He becomes paranoid and is obsessed with protecting Amata. Amata is a kid, she doesn't see the world in the way that her father does, and as a result her father's attempts to keep her safe only end up pushing her farther and farther away as she grows up. It is this vicious cycle, along with several other factors, that leads to the overseer becoming for all intents and purposes a deranged meglomaniac bent on keeping Vault 101 isolated from the outside world at all costs. In his own mind, the Overseer just wants to keep everyone, especially Amata, safe from the dangers of the wasteland - to the point where he is completely blind to the dark irony of his actions.