The schemes are as follows:
- drone factory: the one in the demo, self explanatory. Drones/hypno.
- Vampire: Vampires, gothic horror feel
- Chaos: there are multiple ways this one is played, but the theme is the same: it's total chaos.
- Mansion: Maids, servitude, and trying not to piss off the head maid.
- Factory: Robots and Machines. Specifically fuck machines.
- Changeling hive: Slime, changelings, treachery.
- Asylum: Straitjackets, questioning reality.
- Everfree Forest: ???? (I'm not spoilering this one, I legitimately have no idea what I'm going to do with this one.)
If you can think of something, let me know. But I find it unlikely the sirens would co-operate with King Sombra/Flim Flam/Chrysalis. From what I saw in Rainbow Rocks, they seem to be the usurping type and would probably get double-crossed and enslaved right quick.