He plans to spend his life working on this goal with the full support of his men, most of whom he released from prisons and detention centers. That's also where he found Rick, cowering in a broom closet, after opening the front gates to let them in. The 35-year-old ward of the state had been a janitor doing community service for attempted sexual assault on a teenager at the movie theater where he worked.
Cesar had planned to kill him, but his cousin José, one of those he'd come to release, told him of Rick giving extra supplies and reporting abuse by guards. The Slaver chose to spare him, feeling a debt. Cesar has repaid it cruelly, by turning Rick into a traitor to his country, and he will continue using the weak man in this way until one of his guerillas goes too far in the beatings, and kills the man. The slaver will then find another hostage of lust, and hold him the same way.
The flesh peddler's men are not loyal, trusting, or trustworthy, but as a leader, Cesar is very smart. He makes sure his men have everything they want, to keep them in line: freedom and adventure, whiskey and guns - no limits beyond his share of the plunder, and females, some of them not even old enough to have hair anywhere but their heads. It's all he'd promised them and more.
This very large group of hardened criminals has slowly been moving north, clearing towns along Interstate 25. They emptied stores, burned businesses, homes, and, when they felt like it, whole neighborhoods of scared, defenseless survivors - making examples of any try to stand and fight. The word was spreading quickly from fleeing refugees, and whole communities of people were running.
Most of the small, doomed groups in the Slavers' path fall easily, but some of these ill-fated survivors barricade their cities and made a stand. They lose, and pay the ultimate price, but like so many in this country's violent history, they die fighting - as American heroes.