The thread you've set up has been closed, so I'm just going to leave a couple ideas here.
The Oracle could be a young adult who seems to belong in one side but really belongs with the other (i.e police informant, Mafia spy etc), which could work well to establish the story (these are the two sides, this is their relationship with each other, this what the Oracle is like etc.) The prophecy is delivered, however (maybe they just wake up with a notebook titled Prophecy in one hand or something) but it's written in some unknown language so that the Oracle cannot translate and is left unfinished. Recognising that they just wrote a prophecy (it would have to be a common enough occurrence in this world that they knew what it was or maybe their great grandmother was an Oracle or something) they agonise over which boss to send it to, before releasing it to the internet (or equivalent) so that both sides start on equal footing.
The prophecy is everywhere in the next couple of hours, a cause of much speculation and panic, and so the police and mafia get wind of it. They hire/kidnap a translator (could be a cause of conflict, depending on how many there are around, how easy they are to find, whether they actually want to work with the people trying to hire/kidnap them) and translate the prophecy, which the general gist of is:
'So-and-so Great McGuffin Weapon is up for grabs and could totally help you in this little Mafia/Police stalemate thing going on, putting you in a position of power and so on and blah blah blah, and oh, by the way, it's in-"
And so, to get the rest of the prophecy, they need to get the Oracle. Maybe both sides hire the Oracle to hunt themselves down because that would be hilarious. It could be that the Oracle still doesn't know what the prophecy means. The weapon can be mythical, magical, technological or whatever and the prophecy shouldn't rhyme because it's been translated from one language to another, and anyway, what reason does it have to rhyme in the first place?
Of course, now that I mention it, instead of just the police and the mafia racing to see who gets it first, there could be other groups as well, all with different motivations. What about a group of Oracles who want to induct this new one into their group, or to teach them, or to get them into their favour so they can make power plays over other Oracles? What about a new crime organisation that needs the weapon to pull the mafia out of their little crime niche? Surely other countries and the government would be super interested too?
They could make alliances with each other or fight with each other or so long. I hope the Oracle keeps this a secret for almost the entire story, but they might have no reason to. Maybe phrophesising is illegal and as soon as the rest of the prophecy comes out their head will be cut off. Maybe Oracles are ostracised. Maybe they like the way their life is at the moment and doesn't want anything to change. Maybe they're struggling over who their true alliance is with.
But either they tell someone or they find out somehow, because you don't keep secrets like that forever. Maybe someone betrays them? But all of a sudden it's like hell itself is after the Oracle and they're on the run. Maybe they hide somewhere or fight back? Maybe they make a tentative alliance with someone outside the city's power-system or maybe they hook up with friends or maybe they go it alone. Anyway, there is probably a lot of conflict and the Oracle will probably be captured once or twice.
Anyway, sooner or later, the later half of the prophecy arrives and after last time the Oracle sure as hell ain't putting it up on the internet (or maybe they do, because they're an idiot). If the Oracle is captured at this time the person who captured him will have it anyway and now they have the sweet problem of finding a translator (or maybe they have one already, because otherwise how did they translate it last time?). If the Oracle isn't captured they most probably want the translation of it anyway, or maybe they wanted the translation all along because I'd want to know why a f*ck-ton of people were after me as well. So they'd have to kidnap/hire/rescue a translator.
This would probably be the climax point of the story. And because it would be boring for the Oracle to be walking to the McGuffin by themselves (unless that's going to be used as an epilogue), the end of the prophecy needs to be leaked (betrayal?). Now we have the various forces converging on a single point and there is a fight-fest. It would be nice if the Oracle got hold of the weapon somehow and had to chose which side to give it to, finally deciding who they're loyal to. The best case scenario would be if the weapon was somehow nullified or broken. It otherwise depends on who gets it and what their motives are and what the weapon actually does on what the ending is.
I have no real ideas to the characters other than that the relationship between the Oracle and whoever they give their information to should be interesting. XP
Other ideas for this storyline:
The Oracle gives the prophecy in full and understands it but puts it on the internet anyway/it's leaked out somehow (again, betrayal). However it can only be partially translated (although why they just wouldn't put up a translated version is beyond me). Thus, conflict as they try to find the Oracle to translate the rest.
The Oracle is someone else entirely, a child maybe or someone close to the original Oracle. The original Oracle protects them.
The Oracle translates the prophecy themselves and goes off to find the weapon. Knowing there's a prophecy, but not what's in it, everyone else comes after them.
The setting/genre for the story line I thought up is maybe 20 minutes into the future with hints of (urban?) fantasy. A lot of action/thriller stuff with elements of politics (dunno if that's the name for the genre I'm thinking of). Maybe the city is a city/state? It's definitely a little rundown and a lot corrupted.
Pretty much the setting for this will have to include elements of fantasy, but here are a couple ideas that don't include fantasy in any way:
The Oracle is a fraud/insane. Maybe they're trying to provoke the Mafia or Police into fighting each other, or maybe they're working for one side trying to topple the other.
Somebody has invented a machine that predicts the future.
People from the future come to the past (or claim to come from the future).