Please hide WN/LN/manga spoilers.
MAL entry, Anilist. The zeroth episode is a spin-off-ish, focusing on Sylphy after the Calamity meeting with Ariel, becoming “silent Fitz”, and struggling with her new situation; as well as the power struggles between Ariel and her brother I-always-forget-his-name for the Asuran throne.
O wow, so that’s what it was. Not obvious at all. Thanks for mentioning it. I kind of like her with white hair and totally sets up the option for Rudy to not recognise her in the near future.