>>536565030
Sonia is the "rich one" Sonic is the "normal one" Manic is the "poor one" and all of their character traits revolve around that comparison and all of the tropes surrounding it. Manic is the most subversive of the three.

He has no special powers. He has to use a hoverboard to keep up with his siblings. He is an expert marksman and pickpocket. He has all the general dexterity skills.
He isn't insecure about this. But he does consider that he might not add much to the team at first.
He is nicer than both Sonic and especially Sonia. He has to warn Sonic to be gentler with Sonia (Sonic proceeds to make Sonia cry without a second thought).
Manic is also the least intelligent of the three. The most easily scared. The warmest, and the happiest.
He is also a habitual theif.