Lucifer's personality is given fairly easily. He is goofy but also similar to Willy Wonka's personality. However we can see that Lucifer can have a serious tone to him since Charlie does say that her father wasn't happy with her plans with the hotel.

Lucifer has a wonderful daughter named Charlie Morningstar, and had a wife named Lilith. 

Lucifer is the king of hell, and he takes his job rather seriously— but can be goofy and silly when the moment is right. 