Sivo was a Rogat Orjak companion and friend of Sir James Eglamore. He is most likely of slovenian origin, as most Rogats come from there, and Eglamore speaks one line in slovenian to him after his demise.
Little is known of Sivo, but he has been a friend of Surma Carver, Anja Donlan, Donald Donlan, and James Eglamore (whom he also assisted in protecting the court) for some time, probably since James started his training as Protector of the Court.
At one point, years before the start of the main story, Sivo tried helping them capture Reynardine. The two fought one-on-one and Reynardine won which ended in Sivo being possessed. This was over 5 years before Antimony Carver started attending the Court (7 before the stories current time).
For over five years, Sivo's body was used by Reynardine under the imprisonment of the mentioned group who tried to find a way to remove Renard without killing Sivo. During this imprisonment Renard-Sivo attempted to escape at least once. This attempt ended in him meeting Antimony carver, which later lead to her finding him in his cell. When she did so, Reynardine finally escaped Sivo's body, meaning it was now truly dead.
It is not known what become of Sivo's remains.