What's interesting about Ramandu's daughter is that she's not interesting. There are hints that The Voyage of the Dawn Treader is meant to be the book in which Caspian finds love, but we never really hear much about his feelings, just that he doesn't like the squinting, freckled daughter of the Duke of Galma and that he's awed by the daughter of Ramandu, the star at rest. Ramandu's daughter doesn't even get a name, for crying out loud, but she does get to be Caspian's queen. It's interesting to think about why Caspian's love interest can't be a fully developed character like Queen Lucy. We wouldn't be the first people to observe that C.S. Lewis doesn't seem comfortable with strong adult women as characters – the only females in the books who are both developed characters and on the side of Good are young girls like Lucy Pevensie.