Alistair wants to be ruler of hell. His deal with Charlie makes her do him a favor that will not harm anyone. Now remember that. So Alistair's random disliking of Lucifer was always odd to me. But what if the wants to take his place. I think that somehow Lucifer is going to die. By Alistair's hands or something else's. And Charlie being the princess will then become the Queen. What if Alistair once Charlie is Queen uses their deal to make Charlie give the crown to him. The only problem with the theory I can find is could this be considered a favor? Is giving someone a title and power considered a favor? It's the only argument I could find against the theory. Since favor is kinda loose wording I don't really know. But that's my theory. If it happens it's probably gonna be at the end of season 2.