Editing Big List of RPG Plots (section)

=The Little List of Nearly-Universal Plot Twists That Work With Almost Any Plot Ever=
* The PCs must work alongside an NPC or organization they'd rather not pal around with (those who are normally rivals or villains, or just a snooty expert sent along to "help" them, etc). 
* The victims are really villains and the villains are really victims. 
* The PCs meet others who can help them, but won't unless the PCs agree to help them with their own causes. 
* The villain is somebody the PCs know personally, even respect or love (or someone they fall for, mid-story). 
* The PCs must succeed without violence, or with special discretion. 
* The PCs must succeed without access to powers, equipment, or other resources they're used to having. 
* The villain is a recurring foil. 
* Another group comparable to the PCs has already failed to succeed, and their bodies/equipment/etc provide clues to help the PCs do better.
* There are innocents nearby that the PCs must keep safe while dealing with the adventure. 
* The adventure begins suddenly and without warning or buildup; the PCs are tossed into the fire of action in scene one.
* The PCs must pretend to be someone else, or pretend to be themselves but with very different allegiances, values or tastes.
* The PCs can't do everything and must choose: which evil to thwart? Which innocents to rescue? Which value or ideal to uphold?
* The PCs must make a personal sacrifice or others will suffer.
* The PCs aren't asked to solve the problem, just to render aid against a backdrop of larger trouble: get in a shipment of supplies, sneak out a patient that needs medical help, or so on.
* One of the PCs is (or is presumed to be) a lost heir, fulfillment of a prophecy, a volcano god, or some other savior and/or patsy, which is why the PCs must do whatever the adventure is about.
* There is another group of PC-like characters "competing" on the same adventure, possibly with very different goals for the outcome.