Matthew

Matthew is the main playable character of Golden Sun: Dark Dawn. He is the son of Isaac and a Venus Adept himself. He was first revealed for the game alongside his party members Karis and Tyrell.

As a playable character
It is evident from trailers that he is the main character the player controls in the overworld of Dark Dawn and appears in battles, and he uses a similar collection of Psynergy as Isaac did in Golden Sun, indicating his element as a Venus Adept. The E3 2010 floor demo footage showing him in battle shows him using a thorned plant Psynergy that looks like a 3D rendition of the Thorn Psynergy series, as well as a confirmed return appearance of the Ragnarok Psynergy. Based on retrospective logic, the Move Psynergy that is seen being used in trailer belongs to him as it had to his father.

Biography
He is considered the son of the previous games' Isaac on the basis of nearly identical appearance, the same yellow scarf, and what is confirmed from press releases that 30 years had passed in between Golden Sun: The Lost Age and Golden Sun: Dark Dawn and that the main characters of the game are the children of the main characters from the previous games. In the E3 2010 trailer, he and Karis are seen at a town watching a Psynergy Vortex pulsating in the vicinity. Screenshots show another blond-haired adult in a blue trenchcoat, and one of then shows Matthew specifically addressing him.

In one scene at a floor demo in E3 2010, a Mercury Djinni addresses Matthew as "a Warrior of Vale", which may carry interesting implications.