Anything
How was he to know she wanted a smiling prince and not a dark knight?
He would've become one, if only she had asked. But she never asked for anything. No, she just sat there quietly, like a mysterious riddle-book he would never be able to figure out, because it remained closed. Still, he had protected her- kept her safe from Larxene's constant bullying, tried to keep Sora away from her when he saw how upset she became as he made his way closer to the last floor. But she had never asked for any of it…
How was he to know she wanted to leave this place?
He would've swept her up and carried her out the door, if only she had asked. But of course she was silent when being watched by the Organization members. She was even quiet when it was just the two of them. Not once did she suggest that they should go somewhere, anywhere to get away from those horrid black-coats. Still, he had reminded her that he would always be by her side- that to this day he kept the good luck charm she had given him. Even though she had never asked him to…
How was he to know she didn't have a heart?
His false memories told him otherwise. And with Sora's sudden appearance he had figured it was just the keybearer's return that had thrown her off-balance and made her seem so miserable. She had never tipped him off to how she felt- or rather, how she couldn't feel. He had foolishly thought she could love him, because he loved her oh-so much… even though she had never asked him to.
How was he to know anything about her?
Their whole relationship was built on lies, strung together by others. Yet even after she broke his heart, he held onto the one shard that connected him to her. The one, glittering, warm shard of light left of his dark and destroyed heart. A memory of her smile- sad, tragic, and hopeful. He held onto that beautiful image in his last moments, as he was slain by the real Riku, as he raised his blood-smattered face to the sky. A slow smile crept upon his face, as his final words were uttered in a whispered breath:
"I would've stolen that sky for you… if only you had asked."