Xemnas told her she was different.
Xigbar said she irked him.
Xaldin suggested indifference.
Vexen said she was special.
Lexaeus rarely spoke.
Zexion probably had to do with her creation.
Saix despised her.
Axel was an ally.
Demyx was friend to all.
Luxord invited all to play.
Marluxia called her important.
Larxene called her toy.
Roxas was so much more. He was every memory Xion had for herself. When she realized her very existence hurt his, she knew something must be done. Vexen had created her. She did not wish to vanish, but she dreaded worse the thought of him fading away. Xion found Namine, in a way, part of herself. Were it not for Namine, she might not exist at all, Xion thought. Roxas had to remain, at whatever cost. Xion had braced herself. Or so she thought.
They'd forget her. Everyone would forget her. Even Roxas. No proof of her existence would linger. It would be like she'd never been. It stung her.
But she wouldn't let him fade away because of her. So she fought him. It was a battle for the right to be. She was thrilled and terrified when he won and she fell to the ground.
Xion was shattering as Roxas held her in those final moments. He had confusion and concern on his face. He cared about her, but he didn't know why he grieved for her vanishing. Her hand fell and he caught it.
"Who will I have ice cream with?"
Those simple words lifted cheer where Xion's heart would have been. She was able to smile weakly at their farewell. He would remember her, if even just a little bit. It was enough.