Someone who has an inability to draw anything but Rainbows and everytime they see a rainbow is mesmerilised by it and can't stop looking at it. Overall someone obsesed with Rainbows. Is common to happen to people between the ages of 13-25 although has happened to some 6/7 year olds. Seen as a disease by some people but not contagious or serious in any way.
Evie Realised she had Rainbow Compulsia when she found that in her art classes she could draw nothing but Rainbows.