Nemo clearly heard Idan's offer to become their champion, their representative in this world. However, they themselves did not understand what this meant.
Nemo already roughly knew the couple's story and the reasons why they ended up in this place. When he first met them in the Doppelganger Forest, he had no interest in them. If it wasn't for Izzy, he would have left them to die.
But now, more than two months later, from a chance encounter in the Forest of Doppelgangers, they have become one of the closest people to him.
Nemo didn't remember anything about his past: he didn't know his real name, where he was from, or how old he was. He had no idea about his parents or other siblings, if he had any. All that connected him to the outside world was just the pendant that hung around his neck.
