He and Gabby are the only humans to appear in the whole show (until Santa Claus in the two Christmas episodes and Commander Megan first seen in Robots in Space). Judging by his skin tone, AJ might be Caribbean or African.

AJ (also known as A.J.), is an 8-year old boy and the deuteragonist in Blaze and the Monster Machines, Blaze's driver and his best friend.