I feel like this is self explanatory

So either your Oc is part of the mafia, maybe even leading it if you want things to be more exciting, or maybe they're a cop trying to shut down the mafia.

Maybe their crush or best friend is the cop instead

Or they're part of the mafia with them

Or they're both cops trying to shut the family down

Idk whichever scenario works for you. Maybe make your own and tell me. I'm running low on inspiration so bear with me-