- "It's business. We run a service, she knew the rules. She should have read the small print."
- ―Mr. Santo to Luis Lopez.
Santo is a loan shark in Liberty City who lends a loan to Luis' mother, which she struggles to pay off. Luis assumes, possibly correctly, that Santo also loans money to other people -- and as bought up by Luis multiple times, they may be other old ladies.
Events of The Ballad of Gay Tony
If Luis takes a dive, Santo will appear in Adriana Lopez's life again, helping her with shopping. In a call with Luis, he unsuccessfully asks her not to talk with Santo anymore.
- "You're a fucking dead man. I'm gonna burn that bitch mom of yours, too."
- ―Santo threatening Luis.
If Luis doesn't take a dive and finishes off his third opponent, outside the cage fighting club, an enraged Santo attacks Luis with a knife, forcing Luis to kill Santo.
- Momma's Boy (Can be killed)
- It is likely that Santo is canonically supposed to die in Momma's Boy, since Luis is required to take less than 10% damage in order to achieve 100% gold completion for the mission, which cannot be done if the player chooses to take a dive.
- If the Luis takes a dive, his mother will call him after Clocking Off, telling she saw Santo again, helping her out with her shopping.
- Santo, like Gerry McReary and Ray Boccino, is much taller than all other characters in cutscenes. During gameplay he is the same height as all others.
- He seems to know about Luis' former stint as an underground cage-fighter, suggesting that he has some connections within Liberty City's criminal underworld.