It could use fleshing out, but I kind of like it the way it is. It's just a few thoughts on either side. Feel free to flesh to take this imagery and run with it.
I like rainbows. They're fun. They're pretty. Kind like sunshine, only more colorful, you know? But rainbows don't have my favorite color. MY favorite color is red. Not the red in the rainbow, but deep, crimson red. Kinda like blood, but not quite. That's my favorite color. Why? blush It just is.
She's a rainbow. A sunbeam made of different colors. She's a rainbow, especially because of the way she shines brightest when it rains hardest. She's the one, even more than Tidus, that keeps the group lively and laughing. When everything is falling apart around us, she keeps everyone smiling. Mostly, she's a rainbow because she's the kind of thing you can admire, but never hold.