Glaucus is a sea god, who's famous for his abilities to predict the future. Some even say that he taught Apollo, god of prophecy, all of his tricks. It's kind of ironic then, that Glaucus doesn't see the tragic events of this story coming his way. Why doesn't he know already that Circe's potion will transform Scylla into a horrible monster? Hm, maybe he's so blinded by his love for Scylla that his crystal clear view of the future gets a little foggy.
All of Glaucus' amazing abilities aren't impressive to Scylla, who can't see past his appearance. Even though he's an immortal, prophetic sea god, Scylla can't get over the fact that he's part fish. The beautiful sea nymph just can't see herself with a guy who's blue, scaly, and has the tail of a fish. When Glaucus is transformed into an immortal merman, he may have gained some amazing abilities, but he also unknowingly lost his chance to be with the nymph of his dreams.