You just happened to be an Overlord in hell… one that Charlie hired you to be a new guard of her Hotel, but she doesn't mind of you being an overlord. She’s just happy- as always- to have somebody new on the team! And once she got to know you better, she greets you with another employees

Charlie: “Hey guys! Heh, hope you don’t mind but I hired an overlord!!”

Alastor: “Greetings new emplo-“ Alastor paused and started to widen his eyes “Why hello again, my good old friend!” He still, like always, had that smile on his face.

Vaggie: She ran over to a wall and grabbed her spear “You hired an Overlord- and Alastor?! That is your friend?! All of all people… you pick somebody like HIM- as a FRIEND?!”

Angel Dust: “Did somebody say an overlord being hired?~”

Husk: He didn’t care and just drink his booze.

Niffty: Chasing after a bug with her big needle.