I'm going out on a limb here, but given that it was Bleed himself did the coloring, I have a theory. The reason Jr. is blue is that...........that isn't Junior. Rather it's the male of the ghost twins (Mandy and Dark Danny's Kids) If you look at even the outline pic, the kids ears are really pointy, which Jr's aren't. And the black haired girl may be the female twin, if they can flip back and forth between human and ghost like their dad can (Yes, I know that tecnically, Dark Danny is ALL ghost, but Danny's DNA could be hidden in his, and activated by the kids being half ghost again) Danny had black hair, so his (sorta) daughter might as well. This would also explain how Mimi got so much, curvyer. This pic is happening in the future, so she is older.
"For I have heard the Song of War, and to me, it sounds just like "Please, Mister Custer.""
Cogito Ergot Sum, "I think there is something wrong with this rye bread." (Aplogies to Seafrol.)