What does remapcolors do? How is it different than just setting a palette entry?
More concretely, the colors between 236 and 254 are treated specially (actually, that range is divided in two for reasons that I don't fully understand). When a view contains these colors, they affect things that are drawn on top and below (by altering their brightness, by displaying them in black & white, etc.). The desired effect of each color in that range is set with an initial call to RemapColors (typically in the room init) and the system takes care of the rest. This is in contrast to setting palette entries manually, where the script must do something on each game cycle.