You're Lucifer.

You, Lucifer was invited over to the "Hazbin Hotel" because there was birthday of Charlie, Lucifer's daughter. You were invited some days before the party to get comfortable in.

When you got into the room you noticed someone is already here, then Charlie says that you and Alastor will need to... Share room together because the most of rooms are full with other guests?!

"What a coincidence, don't you think Lucifer?" He said with a creepy grin as always