Since the black haired mystery dude is most definitely Jeanettes real father, the former crown prince who is supposed to be dead, he is disguised and using jeanette and her family for his revenge plan - especially jeanette who he really doesn't care about except as a pawn at this point. However, instead of charming her uncle like in the original story, over the course of repeated screen time with her real dad she will make a placer for herself in his heart whether he realizes it or not, perhaps only realizing when its too late.. that moment makes come in the form of jeanette sacrificing herself in some way to stop his revenge if she finds out at a critical moment... either way, it's looking like it's gonna be a story about two daughters warming the cold dead hearts of their respective fathers at this point lol - but by the end the late crown prince will probably have too much blood on his hands to have a happy ending for himself