Full Name: Crown Prince William Reign
Titles: Prince, Crown Prince, later King, and Chief
Voiced by: Chris Hemsworth
Age: 25 during the prologue, 26 during the events of the show, 27 during the aftermath
Species: weapons master (he's the only one in the family that is not an aetherbender)
Powers: create weapons out of nothing and use them
Abilities: see above^^
Weapon of Choice: what he creates
Mentored by: his father
Family: King Ryker (father), Queen Ophelia (mother), Prince Jasper (little brother), Princess Rosalia (little sister), Chief and Chieftess of Northern Water Tribe (in laws), and Princess Yue (sister in law)
Friends: Team Avatar, inhabitants of the Aether Realm, casters, Prince Zuko, the White Lotus
Enemies: the Fire Nation, the Fire Lord, Prince Zuko (formerly), the witches
Love Interest: Princess Caitlyn (his wife)
Occupation: Crown Prince of the Aether Realm, later moved to become King of the Northern Water Tribe
Alignment: HERO
Loyalties: to his kingdom (both of them), his home, his family, and his wife
Outfits: above^^
Backstory: Not much is known. He was the eldest son of the king and queen and much was expected of him. When he got older, he went on many diplomatic missions to gain allies all over the world. On one of these, he met Caitlyn. It was love at first sight. They've been married ever since.