Fatum Tenebrae

Sebastian SallowxMC

Cassiopeia Black was homeschooled until her fifth year, when her father unexpectedly set his sights on Cassi finishing her schooling at Hogwarts; he claims so she can find a pureblood husband, but she knows he's hiding something much more sinister.

Taking place during the trio's seventh year, with intermittent flashbacks through their times together, Cassi's decision to become a Keeper of the Ancient Secret will come back to haunt her as Sebastian goes down a darker path than expected. With deep familial ties to dark and ancient magic, Cassi finds herself, Ominis, and Sebastian in incredibly strenuous situations that require increasingly darker forms of magic.

Meanwhile, something dark stirs in the corners of the Wizarding World. A dark syndicate, whispered by name as the Mortuus Regulata, has a goal in mind: accessing a forgotten form of magic used to take away all emotions and personhood in order to pacify Muggle masses, allowing for experimentation of darker sorcery, and no longer needing to live in secrecy.

Will Cassi be able to pull Sebastian from his path, or is her path also set in stone?

Important notes:
-CW: implied child abuse, murder
-Any sexual scenes contain consenting characters ranging ages 18+
-Hogwarts schooling, in this iteration, is 12-19, rather than 11-18, making the trio 17, 18, and 19 in each respective year at school
-HEAVILY influenced by the fic Tempest by orangemochafrapp
-Timelines and events have been moved around to fit the narrative, while still loosely following the Hogwarts Legacy story