The first humanoid robot created by Dr. Light, Proto Man plays by his own rules and pushes for independence, even if it risks his own life. Aside from that, he's cool, collected and mostly a lone wolf, though not without a moral code. Sensing that Dr. Wily's going to Battle & Chase to steal the prize zenny, he joined the race with the Red Striker to stop him and win it himself fair and square.

Honestly, any take on him is welcome. Just make him a character that oozes mystery from his aura, and you're golden.