Riddle is lucky to have such a good friend helping him in exploring the ruins! My OC can't even go to the sun side. He'll probably burn there immediately.
He is a vampire, so he isn't able to go into the sun at all. I might consider changing that, because I'm always forced to draw him on a night/dusk background or inside a building. And some portals might require him being outside during a day.
Perhaps he could have a special outfit that allows him to be outside during the day?