Aden is the main character throughout the entire main story of the game, but at the end, if you choose to be Sonja, Aden will become a romance option. He is an Earthmate, one that can communicate with the spirits to help farmers allow their crops to grow. He has been best friends with Sonja since they were children, but often finds her attitude annoying.
Birthday: 14th of Fall
Likes: Rice Dishes (except Porridge and Risottos)
Hates: Cold Medicine
* A Cutscene is needed to progress Aden's relationship beyond 8 hearts. Visit the Church Plaza as Sonya (after the main story of course) around 11AM to trigger an event to advance the relationship. (Extra gifts beyond 8 hearts are required since the character needs to be ready to advance to 9 hearts for the event to happen.)
(Thanks, Anita for the information.)