Peter Kitsuné doesn't talk much about his past. He vaguely mentions arriving in the Old World in mysterious circumstances, with no idea how he got there or where he was. He actually isn't native to the Old World, but rather comes from another world named Furth. On Furth he received an ancient curse, which would have eventually killed him, or worse. He sometimes mentions how his first calling, before he became cursed, was that of a demon hunter.
In time, Peter signed up for the adventuring guild and went through the Portal into the New World. The first thing he discovered was the magic - thick enough he could almost taste it. The second thing he noticed was that his curse was gone. Or - not gone. But suppressed. Something about the New World meant the curses of Furth didn't function here, or something.
Now, having achieved a limited amount of primal magic, he is willing to group up with some strangers and fight foes together that cannot be fought alone. And maybe even make some new friends?
Either way, it looks like they're going to have a good time here in the New World, Beyond the Portal.