This is information is cited directly from the Hazbin Hotel Wiki (because I'm not about to write information for a character that has existed for over  six years)

He is the wickedly charismatic demon who has offered to assist Charlie Morningstar in her endeavors, albeit, for his own amusement. Alastor stands out from many of the more chaotic residents of hell for his well maintained amiable persona. He gives a first-impression of a good-natured and charming man, wearing a permanently wide grin on his face at all times. His behavior, mannerisms, and even his voice are similar to an old-fashioned radio announcer and speaks with a transatlantic accent