One of the most important through-lines to this season is Fiona's desperate attempts to maintain power at all costs. Tradition (and magic) dictates, however, that one Supreme must die to give way to another, so Fiona is cursed with incurable cancer. She's not about to go down without a huge fight. In an attempt to learn the secret of immortality, she frees Delphine, the suspended-in-time slave-hunting prisoner of voodoo priestess Marie. And when Fiona suspects Madison is going to be chosen by the magic as the next Supreme, she murders the younger witch and has her loyal butler Spalding help conceal it.
Fiona's rival Myrtle suspects something is off about Fiona, and she doesn't hesitate to call her out on it. Myrtle figures out that Fiona murdered Madison, which does not sit well with the Supreme witch. After Cordelia is the victim of an acid attack by witch hunters, Fiona uses the opening to frame Myrtle and have her burned at the stake.