Nathan was born to Chris Sullen and Angela Felix, who died 6 months after his birth in a fire. From a young age he has spent many days in the hall of justice along with his father, and has been trained in martial arts since age 9 by different leaguers. When he was 10 he took up the monniker of SkyRim and has been a sidekick to his dad ever since, and became the youngest member to ever join Young Justice at age 11, and becoming their leader at age 13. Both his parents were flyers and he took over that aspect, without needing wings, and he also developed super speed. He is currently enjoying a wellfared education in Gotham Acadamy, where he ranks as the best of his class.