World Apart - The Earthbound Trilogy, #2

Clare and Trevi made their way through a portal to get back to Earth. Instead, they find themselves on a dying world as a mysterious mist closes in. Trevi's scarred twin brother, Celi, has accompanied them. He meets a female magician called Fane, who has been an outcast just like him. In this world only men are magicians and they believe her existence is the cause for the mist. Fane and Trevi learn to trust and eventually love each other as they fight to find a way to save the world.
There are people who want Fane dead and to use her to get off the dying world, but Celi will use all his powers as a vampire to stop them.