Cézar was born in Rhylenor to the Dimas tribe. He is 39 years old. Slavers from Skystead captured him while he was hunting with two other tribesmen. He is not aware whether those two tribesmen were killed or taken as slaves also. Either way, he hasn't seen them since. He was fifteen when this happened.
The slavers that captured him are not a recognised group and in fact, many people living in Skystead aren't aware that people are being trafficked under their noses. It's a murky, secretive business. Slaves are passed as servants supposedly receiving wages to those who question.
Cézar was given to an Estrian lord and worked under this man for two years. When he was nearly eighteen a group of mages visited the lord and when he offered to take one man's horse to the stables, the mages each turned their eyes towards him as if they recognised him. Later, Cézar would learn that they were members of the Inquisition and that they had merely sensed his potential.
The mages managed to encourage the lord to drink enough that he revealed to them that Cézar was a slave and even offered to sell him. Cézar was promptly freed and brought to the Mages' Guild where he was enlisted into the Inquisition. It had been years since he tried to use his magic - the separation from the forests of Rhylenor had tormented him enough - and it took some months of training for him to regain his former talent. On the field, Cézar wields a heavy battleaxe.
Cézar met Aluna and Friederika upon joining the Inquisition and they became fast friends. We can plot these relationships a lot more when he's in play! The rest of his history & personality is open to interpretation.