
If you watch delicos nursery, you can actually see baby Sophie when his village got burnt down. The reason why Sophies village got burnt down is because of krauss/klaus, a person from the village begged for eternal life and I assume krauss got annoyed because of people begging for immortality(and I assume majority of it are dhampirs) and made the people in nebula village kill their own people (nebula village is where Sophie was born, the village consists of dhampirs). 3 only survived after that incident happened. Those three happened to be Sophie, banri, and a guy named julas(?), you'll find more information about julas in delicos nursery

Honestly the younger sisters reaction is real if I'm being honest if I were in her situation I would tell my older brother that his classmate is creepy. If she gets killed I would honestly have expected it ngl, she probably isn't aware that guy also kills just for tokieda and only thinks he's a weirdo around her older brother
I hope pengki makes a short story about bun-gae and the secretary from sung yuns family