Gaius is the Ex-Commander of the Order of Sydon in Mytros. Before being replaced, he had a silver dragon, as well as command of knights and fighters across the Settler and Native races as part of his role.
He has been banished from the city of Mytros due to his involvement with the Minotaur Slave Trade, which is what lead to his replacement as commander by Yala. In addition, bound by Oath, Gaius is currently unable to return to Estoria due to a deal made with the Oracle's Chosen.
Gaius stole some jewelry belonging to Calliope from Xander Huorath's tomb at the Necropolis at Telemok. He has sworn an oath to return it to her if she visits his chambers on Yonder.