Disclaimer- I don't own Kingdom Hearts II.
The very first thought that crossed her mind when she saw him wasn't about Sora, or the Keyblade, or memories that were shattered like brittle glass.
It was, quite simply, this.
He's like me.
She didn't know if that was a good thing or not. He didn't have a heart- how could he? He was a Nobody, a nothing among nothings, and the only reason he still existed was because he was too stubborn to let go.
Then again, wasn't she the same way?.
When he spoke to her, she felt something- which was impossible, because she was nothing, he was nothing.
That sparkle, that glimmer of something that was purely Roxas couldn't exist- not unless it was a shadow of another's heart.
She had to believe that- her entire world was centered on the fact that she was nothing.
So when Roxas' voice softened and his eyes gazed upon her with something warm in their few stolen moments, she forced her -not-real- heart to slow down and think rationally again.
This love didn't exist.
But, given a chance, it might have been worth something all the same.