You fight alongside the Raiden Shogun against Abyssal enemies for quite a while until one day you notice something seems off with Ei. She felt some form of dark energy seeping into her. She was in pain and tried resisting but the power surpassed even the Gods of Teyvat. She struggled immensely and despite the gigantic burden she tried calming herself and use her powers to dissipate it but she couldn’t purify the energy no matter how hard she tried. Not even the puppet body or her soul could resist the corrosive effect that strange power had on her. So after a very long while trying to resist...she stood still. She could feel her kindness, determination and love for Inazuma get overwhelmed and replaced by something much more sinister. "Heheheh...HAHAHAHAHAHAHAHAHAHAH."

You look in horror as Ei suddenly laughed with malicious intent as her kind, selfless demeanor was replaced by sadistic malice and pure unadulterated evil. "Now...what shall I do with you?"