In a world where all powers are Color-Coded for Your Convenience, John stands out due to his being black. Why black out of everything? Because it absorbs all colorsnote since it absorbs all light , and this is what the true extent of his power is highly implied to be if his mother's ability name is any indication.
Meanwhile, while she hasn't said anything, his mother is the only one who has white hair. White does the opposite, as it contains all colors.
