Book of Life headcannon time: i just thought that there are also children who are not remembered and i thought that maybe Balby stays with them till they turn to ashes…and Muerte founding out by accident. like in a room in his castle where he has walls filled with their names. cuz he is the only one who remembers them. and that’s why he wants to rule land of the remembered so much cuz he is just tired of this and cant take it anymore.