Well, I don't think anything stands out as being a problem! If I had any suggestions, it would just be to bring the characters' eyes a little farther forward on their faces; there isn't necessarily anything wrong with it, but right now they're kinda in that magical space that anime eyes go in (not to compare them with anime eyes of course) where they kinda float somewhere behind the surface of the face, and at different angles stay closer to the center of the head than the frontal plane. The only thing I would say other than that is that Bryan's nose came out a little crooked, but that's not a big deal!
I don't know if it makes any sense, but how far left his eye is from the side of his face there, from a 3/4 angle makes it look like his eyes are set really far back on his face - so if you wrench it out farther towards the edge of his face there it feels more like his eyes are in a 3D space with the rest of his head. Know what I mean? I'm probably not saying it well D:
