I firmly believe that when Alastor first came to hell, he went to Cannibal Town and Rosie was his mentor until he was strong enough to become an overlord himself. More importantly Rosie definitely has Al's teenage bedroom that she's left completely untouched in case he decides he wants to come home. What embarrassing posters and trinkets did lil baby Alie have in there and how many dead deer have been kicked under the bed