How we cite our quotes:
Maniac kept trying, but he still couldn't see it, this color business. He didn't figure he was white any more than the East Enders were black, He looked himself over pretty hard and came up with at least seven different shades and colors right on his own skin, not one of them being what he would call white (except for his eyeballs, which weren't any whiter than the eyeballs of the kids in the East End.)
Which was all a big relief to Maniac, finding out he wasn't really white, because the way he figured, white was about the most boring color of all." (16.15-16)
So maybe Mars isn't colorblind, after all. It's almost like he's even better as seeing colors than anyone else—so good that, where everyone else sees the world in black and white, he sees it in full Technicolor.
Grayson had a way of jumping into a subject without warning; it was during Maniac's dessert that he abruptly said, 'Them black people, they eat mashed potatoes, too?'
Maniac thought he was kidding, then realized he wasn't. 'Sure, Mrs. Beale used to have potatoes a lot, mashed and every other way.' (24.4-5)
Yeah, we though he was kidding, too. This just shows how limited Grayson's experience is, and it almost makes us sympathetic. How can you get over your prejudice if there's a line down the street keeping you from making friends on the other side of town?
He knew he should be feeling afraid of these East Enders, these so-called black people. But he wasn't. It was himself he was afraid of, afraid of any trouble he might cause just by being there. (38.4)
It looks like Maniac does feel fear after all—fear of himself. He may not be afraid of black people, but he's afraid of how his not being afraid will make people act. Confusing? Yeah. But when you think about it, no more confusing and weird than dividing people by some arbitrary point on a grayscale.