so the basic overview of my meta plot is that the yuan ti is attempting to gather power within the region and summon some sort of devil/demon that is their god (turns out that they have one Dendar, the Night Serpent, Merrshaulk, Master of the Pit, and Sseth, the Sibilant Death, are listed within the monster manual as their gods)
so i figure that i will start off with all the dumb random crap on the interwebs about the lizard people secretly ruling the world and then just d&d it up. so here is what i have:
due to the uprising of the weird devil/demon cults over the last few years this allowed the yuan ti to get into a position of power in a few different places with either backdoor pay offs or assassinations or even just getting shape changing people to take the original persons place. they have done this in strategic locations so that they can have a finger in every pie that they think they will need, so anyone from the random beggar on the street to the leader of the magicians guild to princesses of the realm, they could potentially be yuan ti.
they have decided that the devil/demon war that happened a few years was good for them and by placing false information about people trying to resummon them or new ones they can actually use this as a cover for what they actually want to do, which is summon their god/gods.
i have a few other random ideas that i am trying to bring together and i have also sort of injected random story elements from various adventure paths that i have at home, the hooks that are currently out there are:
the jewler who delt in stardust
tales from the yawning portal
maze of the blue medusa
so as you can see i have a bunch of potential areas i can take the story, i just hope that it all works out well