Most of the time, he's green, mirroring her eyes. He thinks that somehow it will make her feel better—less alone. (Though, let's face it, at the heart of all things she's the loneliest person in the universe, and his thinking he can remedy that is just a cruel twist of denial.)
Sometimes, though, he changes for her. (It's all for her.) It's a huge asset in hide-and-go seek (a game that makes her laugh), or when he becomes a real-live 3-D representative of creatures she's only read about in books (red and black ladybugs, she thinks, would be her favourite insect of all if she ever got to see one). He's pretty sure he's been every colour of the rainbow and more in the time he's been her constant companion. She's not a demanding person (unlike her witch of a mother), but he feels determined to give her all she deserves anyway.
At night, Pascal turns a textured-looking honey-gold and settles in against the warm skin of her neck. After all, what's another lock of hair to a girl with seventy feet of it? Gothel never notices, and Rapunzel doesn't either. Pascal just grins and chirps himself to sleep.