For to share this, but some sketch attempts at getting better / more familiar with his face! Because he does have this specific LOOK in my brain that SHOULD be simple, but training your hands to stick with the correct shapes can be tricky. Got that broad brick-potato vibe going on. I like the idea of his demonic aspects enhancing depending on his excitement / use of demonic power. It usually involves the embiggening of his horns and teeth, though his hair will light up in a wispy fiery fashion as though it were compiled of inky black flames!

The demons I've been hashing out for my in-universe canon have been so much fun! It's not getting to decide your own rules and specifics for a species once you're able to divorce yourself from real-world ones.