Fen hasn't been described in the book but as per the writer he looked like Xaden. Just a fairer complexion. Sharp features and a handsome face. Silver gray hair and matching silver eyes. He was tall and muscular with a hint of dominance in his aura. His signet is unknown yet he was said to have a way with words. A true leader who could make people follow his lead. Hence he made the rebellion happen against a whole constitution and anyone who wasn't part of it was simply a coward following a lie.