Prophecy

Arthur doesn't meet Silvia and is never bonded with Sylvie. Arthur grows up in Xyrus as a Quadra elemental prodigy. He was never reincarnated so he doesn't have a past life. Lastly Arthur's Djinn blood is a lot more prominent and he's able to use a small bit aether in combat(about the same amount of control as the dragons). Tessia instead is the one who meets with Sylvia and is bonded to Sylvie.

Neither one is going to be the main character over the other as both of them will be mostly equal in strength throughout most of the story .