Ei knew that Wanderer was too vulnerable bcs of his cries, and she thought that he'll suffer if he becomes the vessel of the Electro gnosis. But she didn't want to kill him like what Miko suggested. So she let him to be free, to be happy, to be safe, she also gave him a protection charm to ensure his safety throughout Inazuma. Unfortunately what she lacks was communication, her choice was right but the way she did it miss a step. She should've tell him clearly to avoid misunderstanding...
BRO I SAW THE BIRD FROM EI’S IDLE ANIMATION AND STARTED ACTUALLY CRYING. THE BIRD FROM HIS TRAILER(?) IS THE EXACT SAME ONE WITH EI,(this is a theory) GIVING INFO TO EI HOW WANDERER IS DOING 😭🙏 also, Ei never forgot Wanderer, because all Wanderer changed in the past was what he was about to become, a Fatui Harbinger. He still met his friends and they all died, and Ei still created him