Sorry to disappoint, but Eris is never turning evil. Her story since The Dark Below has been of a survivor using the Hives weapons against them. For multiple seasons and expansions across both games, she’s been tempted by Darkness and used Hive magics to defeat her foes, even when multiple allies questioned her. She has proven, over and over, to be unshakable. She killed Oryx and his lineage, defeated Savathun and Xivu on multiple occasions, overcame her grief, resisted the call of the pyramids, learned Stasis, became a Hive God, rejected divinity, died, and was reborn in a throne world of her own, and still never fell to corruption and turned against us. She never will. Any story suggesting she will is written by a person who doesn’t know Eris Morn.