Lucan is described as being at least a decade older than Gavin, which would place his birth around 130 AYZ. He is the son of Theodor Zosimus, brother to Hugh Zosimus.
A colonel, he retired from military life after he realized he could become the heir to his uncle's fortune. Hugh's widow, Sibylla, considered him as a possible inheritor of the family estate upon her death. While she apparently changed her mind and willed the property to her son Gavin, the state stepped in and quietly altered her will, making Lucan the next Lord of Tyr and splitting the fortune between him and Gavin.
Since then, Lucan's opinion of Gavin has been rapidly decreasing, as he sees his cousin as a careless, irresponsible rake wasting his money and time on pointless ventures. Having no interest in marriage, he began pressuring Gavin to marry a rich woman and produce an heir in the hopes that he would settle down. After Gavin attempted to defect to Norev, he cut all ties with his cousin.