Oh boy this is one of the better of Ms Kenyon's books. A companion to Acheron, we get to see the other side of the story.
Styxx is Acheron's twin brother. Thought for the longest time as one of the villains of Acheron's life, we learn a lot about this very interesting character. In Acheron's novel Styxx comes across as a nasty, self serving bastard and as we all know, you should never go by first appearances.
Styxx did not have the better life that Acheron and their sister believed. Raised with an almost classic abuser it would not be surprising if he grew up to be the ass everyone thought he was, but as what happened well it shows so much more.
Styxx was born with a tight empathic link to Acheron. Every time Acheron felt pain, Styxx felt the same without any visible injuries. Suffering massive migraines and nose bleeds from them in a time period that people had no idea just what they were, this young man was doomed from the start.
He meets a beautiful and blind fisher woman and finds happiness that is all too brief. As his life is tied his brother's, he dies and is brought back to life and dumped on the Vanishing Isle by Artemis.
There is so much more I could tell you but reading this book would be the best way to learn it all. I recommend you read this right after re-reading Acheron. It might be a long read but the two of them together are an amazing story!