Yellow definitely went through some changes in his look over time. He’s much more of a rectangle now, but I still try to make the top of him slightly wider than the bottom, but never as extreme as it was in these first pages. I also draw his eyebrows/forehead almost exclusively the way it appears in the fourth panel, just because I think it looks better.

Red and Yellow bond instantly upon meeting for the first time. Red has a habit of getting along with almost everyone.