He's a human kept hostage by a powerful druid. Theo doesn't remember any of his life from before, but he knows he's magically bound to serve the druid Rowan. Forced to obey every command, he can feel his strength draining day after day. He doesn't know how much longer he can last, and he's only holding on for Marielle, Rowan's daughter who's become like a sister to him. The vampire prince goes to save his sister-and discovers much more. When Silas, the scholarly vampire prince, finds an elixir that will save his sister from a deadly blood poison, he seeks out the druid Rowan to make it for him. Little does he know that he'll walk out with the elixir and the knowledge that he has a mate. He'll stop at nothing to break Theo's spell and have him for his own. True love never did run smooth. Between Rowan's cruelty, Silas' father's belief that mates are a weakness, and a brewing coup in the vampire kingdom, Silas and Theo will have to overcome huge odds to build the life they envision together. A M/M mating-bond spicy paranormal romance, Silas is a guaranteed HEA that stands alone. Theo is a character in Callum, and this book tells his story.