He's not like the others. When Xerneas finds out his father isn't even from his world, he seeks to find out who, and what he is, as well as who his father was. All while possibly saving two worlds.
A team of four. They are huntsmen and huntresses trying to rid the world of the Grimm that have changed their lives. That is not their only goal, however. They wish to be seen just as capable as humans, not weaker, not more dangerous.