Eris

Eris Godess of discord

Eris tempted Eri with a golden apple to possess and use her as a tool to bring chaos into this world. After capturing Saori Kido (Athena), Eris placed a golden apple in front of Saori's chest to drain her power and life force to the point she would no longer need Eri's body, and proceeds with her plan to take over the world. It had been foretold that, if Athena were to die, all of the dead Saints with grief in their hearts would be revived to finish Earth's destruction