I'm working on his personal story (I came up with the idea. Still working on more)

Hearts was found by a Snow Demon whose name is Jacob. Who was strolling through the cold depths of the blizzard forest, there he spotted a demon child not from their "kin" but "them."

Them they refer to "Realm demons" "Outside demons".

Snow Demons - Fact - Eyes cold as fierce ice, skin pure as snow. Hair of silver or gray, of any kind. They live in the coldest habitat on Earth, immune to its deadly nature. Very territorial and strict towards outsiders, such as humans

(Snow demon is what Rosary is)