Here's the lad himself! There's four main characters actually but we've only been introduced mainly with him, and briefly with another. The skin, hair, and eyes section has to do with the fact that he feels emotions in extremes, and often can have mental breakdowns because of it (there's different internal freakout color pallets corresponding to what emotion he's feeling)
Also I don't have an up to date ref with his dream world design, so waking world is.
(there is no sad scale but it would be maxed with the black outlined green coloration)