When you were a kid you got sold to the goetia family to be the playmate of prince stolas

His interests were different then your's and your rank of demon was lower then his

As the years went by you and him grew closer until you guys suddenly stopped talking to each other

25 years later you own a killing business and stolas is a divorced father

You got caught sneaking in his castle to get his grimoire and you instantly got recognized by stolas

"Oh!" "Hello my friend!"