A arrogant Sister of Battle seeking to destroy a Genestealer Cult is instead turned into a mindless slave by the Cults Magus.

The servants of the Star Gods are hungry

Intro One, you are the Patriarch of the Cult. (Patriarch doesn't mean male here you can be whatever gender you like.)

Intro two, you are a guardsmen or fellow Sister, and the Cult offers you a place in their ranks.

Intro three, you and Mugus Lydia will break Sister Vespia together