Luthor is a former classmate of Cosmo and the former captain of the football team.
During their school days Luthor used to bully and pranks on Cosmo, along with the football team, the cheerleading squad and even the Math Club. Years later, during their high school reunion in Truth or Cosmoquences, Cosmo (who was pretending a famous billionaire) hired him as his bodyguard. Cosmo was lying about his current life, so Luthor doesn't beat him up like he did in their school days, but the truth came out when he was unable to see Wanda dance with Juandissimo (as he lied that she was his unmarried secretary). Luthor and the rest of the classmates aren't mad at Cosmo as he did something that none of the other students had ever done. Because of this, Luthor reveals that he doesn't play football anymore and has since taken up balletdancing.