I've seen a LOT of attempts at human Frak designs, and I just have to say, I don't think hanging on the the green in his skin/hair is the key distinction, I don't think mimicking his head scales with the slick back or the mohawk does it, I think what you really need to do is just lean into the fact that as a human, he would be the most severely ginger man on the planet.
Just stupidly bright curls that are a new flavor of messy every time you look at him, freckles so ubiquitous it looks like an optical illusion, a chipped tooth, and just the instantly flushest skin any time he moves even remotely strenuously.






