Prince Sidon

Prince Sidon is a character in The Legend of Zelda: Breath of the Wild.He is the prince of the Zora during the events of the game, he is the son of King Dorephan and the younger brother of Princess Mipha.He has a very enthusiastic personality and is said to be capable of many great feats like being the best swimmer of all the Zora and being a skilled archer.

History
For the moment Mipha's role in the Zelda series is only composed of informations with an unconfirmed timeline placement and should stay this way until we have a definitive answer, so please don't add any information regarding the timeline placement without OFFICIAL confirmation, thanks.

100 years before The Legend of Zelda: Breath of the Wild
Being a Zora, Sidon have a much longer lifespan than any Hylian and say himself that he is old enough to remember his sister who die during The Great Calamity 100 years prior to the events of the game.

The Legend of Zelda: Breath of the Wild
During Breath of the Wild Sidon is first seen at Inogo Bridge where he ask Link help to defeat the Divine Beast Vah Ruta since he can't wield Shock Arrows.He then follows Link as he goes toward Zora's Domain.He is next seen at Zora's Domain where he introduces Link to his father and Muzu and explain the plan to take down the Divine Beast to Link.After that he will help Link in his fight against the Divine Beast, allowing him to board the beast.After freeing the Divine Beast he he thanks Link alongside Muzu and the King.