Seele's origins are a complete mystery—nothing's documented about her birthplace or parents. She lost them early on and ended up at Cocolia Orphanage, where she grew up alongside other kids including Bronya and Sin Mal.
She wasn't considered a strong candidate for Cocolia's X-10 experiment at first, but managed to awaken her abilities just in time and took Sin's spot. Her motivation was purely protective: she wanted to safeguard Bronya. That decision kind of backfired, though—Bronya ended up enrolling in the experiment herself just to find Seele.
The experiment itself, combined with Honkai energy exposure, fractured Seele's mind into two distinct personalities that are basically opposites. One side of her is genuinely sweet and caring toward people she loves. The other is cold, manipulative, and willing to use her powers ruthlessly to get what she wants.
Content compiled by AnimeList.moe from publicly available sources.
