I'm going to go out on a limb here and app for the Overseer. Linna, just let me know if you don't like and I will change it to app for someone else. I'm easy
The Overseer always smiles. The Overseer never raises his voice. The Overseer is young and handsome and always, always smiling. The Overseer loves you all. The Overseer only wants what is best for the Vault. The Overseer is going to take care of everything.
The Overseer likes to see you cry.
Four years ago, Michael Keller was no one. He worked in the canteen, he served food, he smiled. He talked to people. He had a spark in his eyes, a laugh in his voice, a curious inflection that said 'trust me'. He was young and the Overseer was old, old and scared and angry. The Overseer watched his own people and saw plots everywhere, saw traitors and communists who had followed them down from a world long forgotten. He had people killed, people they could scarcily waste. Denizens and citizens and security. He was ripe for overthrow and with a few smiles, a few laughs,one young man with a dream, a spark in his eye, shot him straight through the heart with an old hunting rifle he'd used to kill radroaches in the canteen.
Then he smiled at the Vault and he said to them, "No more worries. The Overseer is going to take care of everything."
And for some people, he did. Security are treated as above the rest of the Vault, they are given anything they could want. They are given very little oversight and very little control. they can do almost anything they want to a denizen and no one blinks. No one complains. It would be a very bad idea to care about a denizen.
Citizens are fed and taken care of and treated well as long as they obey the rules. The Overseer is very big on rules. Little rules and big rules. If you break a little rule, you get to see Allita. If you break a big rule, you may get to see the Overseer. And denizens who break any rule, any rule at all, they go to see the Overseer in his big office with his big doors locked by the very best in pre-war security.
And when that happens, the Overseer smiles.