In Kingdom Hearts Chain of Memories, when referring to Maleficent, Vexen says "Don't be absurd. The witch is gone. She cannot return from the Realm of Darkness of her own volition." This means that after Sora destroyed Maleficent in the first Kingdom Hearts, she got sent to the Realm of Darkness. Why is this? Why did Maleficent get sent to the Realm of Darkness instead of just simply dying? Or did she just simply escape after the battle with Sora to the Realm of Darkness using a Corridor of Darkness? Also, why did she have to wait for someone (the three fairies) to remember her in order to come back when she could've just used a Corridor of Darkness?