Well first, Marcus promised Billy to help kill his dad (who is crazy evil and owes the mafia money) so that his little brother wouldn’t be shipped to King's and his mom can start living her life without an abusive husband.
Locked out of his room, Marcus heads to the casino, where he wins big on a slot machine, and catches the attention of law enforcement. Which leads up back to the moment where he finds himself being interrogated by a cop who gives him a slap on the wrists and a stern warning to stay out of his casino!
It's clear that Chico won't stop until Marcus is dead. Even poor Billy is stabbed by Chico when trying to quell the situation. Maria's rage spills out and she slits his unsuspecting throat with her bladed fan. The gang retreats, leaving Chico's body behind and also...F@#kface, who unbeknownst to our team, watched the whole scene unfold from a dark corner of the alley.