I know he is your OC, and normally he doesn't look like Zuko, but I dunno... It's just something about the hair (and the fact that I have been watching Avatar non-stop lately). And the brooding stare. This one looks like if Zuko had never had the agni kai.
I think it's probably the oppressive atmosphere created by the speedpaint-y watercolor brush and the grumpy expression, that helps too. Plus he looks like he's on a mission in this pic, and Zuko always looks like that...their personalities are polar opposites though. Zuko is reckless, impulsive, and angry, whereas Captain is a puppetmaster-type schemer who places WAY too much value on self-control and self-denial. Either way, I'm glad you've been watching Avatar non-stop lately