Books say he's indifferent. Even his own brothers call him a little cruel. So why is he so good to her? He takes her to all sorts of places, indulges her strange curiosity, and protects her despite her weak demonic powers.
Maybe there's something he wants from her, though she doesn't even know what it is herself. Well, she's afraid he'll just abandon her one day. So she tries all sorts of bizarre methods, only to end up stuck in bed for ages. Honestly, she was only trying to help him, and then he gave her a thorough scolding. She has no idea what that big, bad dragon is thinking... Maybe he's worried that if she gets hurt, he won't be able to get what he wants from her. What a nasty dragon!
Theme: Grow little by little, and gradually learn what love is and what your heart truly wants.