When people are looking for plot ideas or new events to sprinkle into their roleplays, the first place I am going to point them is to this article.
Published first in a french book of the same title in the 19th century, this list has been of a massive aid to writers ever since. Written by french writer Georges Polti, it was meant to categorize every possible situation which might occur in anything from a poem to a play. The list came about after extensive studies of Greek texts, french literature, as well as non-french literature. Polti claimed to continue the work of Carlo Gozzi, who had also, himself, found these thirty-six situations.
Required Elements : a Persecutor; a Suppliant; a Power in authority whose decision is doubtful
The Persecutor accuses the Suppliant of wrongdoing, and the Power makes a judgement against the Suppliant.
Required Elements : an Unfortunate; a Threatener; a Rescuer
The Unfortunate has caused a conflict, and the Threatener is to carry out justice, but the Rescuer saves the Unfortunate.
Required Elements : a Criminal; an Avenger
The Criminal commits a crime that will not see justice, so the Avenger seeks justice by punishing the Criminal.
4. Vengeance Taken for Kin upon Kin
Required Elements : Guilty Kinsman; an Avenging Kinsman; remembrance of the Victim, a relative of both
Two entities, the Guilty and the Avenging Kinsmen, are put into conflict over wrongdoing to the Victim, who is allied to both.
Required Elements : Punishment; a Fugitive
The Fugitive flees Punishment for a misunderstood conflict.
Required Elements : a Vanquished Power; a Victorious Enemy or a Messenger
The Power falls from their place after being defeated by the Victorious Enemy or being informed of such a defeat by the Messenger
7. Falling Prey to Cruelty/Misfortune
Required Elements : an Unfortunate; a Master or a Misfortune
The Unfortunate suffers from Misfortune and/or at the hands of the Master
Required Elements : a Tyrant; a Conspirator
The Tyrant, a cruel power, is plotted against by the Conspirator.
9. Daring Enterprise
Required Elements : a Bold Leader; an Object; an Adversary
The Bold Leader takes the Object from the Adversary by overpowering the Adversary
Required Elements : an Abductor; the Abducted; a Guardian
The Abductor takes the Abducted from the Guardian.
11. The Enigma
Required Elements : a Problem; an Interrogator; a Seeker
The Interrogator poses a Problem to the Seeker and gives a Seeker better ability to reach the Seeker’s goals.
Required Elements : [a Solicitor & an Adversary who is refusing] or [an Arbitrator & Opposing Parties] + an Object
[The Solicitor is at odds with the Adversary who refuses to give the Solicitor the Object in the possession of the Adversary] or [The Arbitrator decides who gets the Object desired by Opposing Parties]
13. Enmity of Kin
Required Elements : a Malevolent Kinsman; a Hatred or a reciprocally-hating Kinsman
The Malevolent Kinsman and the Hated or a second Malevolent Kinsman conspire together
14. Rivalry of Kin
Required Elements : the Preferred Kinsman; the Rejected Kinsman; the Object of Rivalry
The Object of Rivalry chooses the Preferred Kinsman over the Rejected Kinsman
15. Murderous Adultery
Required Elements : two Adulterers; a Betrayed Spouse
Two Adulterers conspire to killed the Betrayed Spouse
Required Elements : a Madman; a Victim
The Madman goes insane and wrongs the Victim
17. Fatal Imprudence
Required Elements : the Imprudent; a Victim or an Object Lost
The Imprudent, by neglect or ignorance, loses the Object Lost or wrongs the Victim
18. Involuntary Crimes of Love
Required Elements : a Lover; a Beloved; a Revealer
The Revealer betrays the trust of either the Lover or the Beloved
19. Slaying of Kin Unrecognized
Required Elements : the Slayer; and Unrecognized Victim
The Slayer kills the Unrecognized Victim
20. Self-sacrifice for an Ideal
Required Elements : a Hero; an Ideal; a Creditor or a Person/Thing sacrificed
The Hero sacrifices the Person or Thing for their Ideal, which is then taken by the Creditor
21. Self-sacrifice for Kin
Required Elements : a Hero; a Kinsman; a Creditor or a Person/Thing sacrificed
The Hero sacrifices a Person or Thing for their Kinsman, which is then taken by the Creditor
22. All Sacrificed for Passion
Required Elements : a Lover; an Object of fatal Passion; the Person/Thing sacrificed
A Lover sacrifices a Person or Thing for the Object of their Passion, which is then lost forever.
23. Necessity of Sacrificing Loved Ones
Required Elements : a Hero; a Beloved Victim; the Necessity for their Sacrifice
The Hero wrongs the Beloved Victim because of the Necessity for their Sacrifice
24. Rivalry of Superior vs. Inferior
Required Elements : a Superior Rival; an Inferior Rival; the Object of Rivalry
A Superior Rival bests an Inferior Rival and wins the Object of Rivalry
Required Elements : two Adulterers; a Deceived Spouse
Two Adulterers conspire against the Deceived Spouse.
26. Crimes of Love
Required Elements : a Lover; the Beloved
A Lover and the Beloved enter a conflict.
27. Discovery of the Dishonour of a loved one
Required Elements : a Discoverer; the Guilty One
The Discoverer discovers the wrongdoing committed by the Guilty One.
28. Obstacles to Love
Required Elements : two Lovers; an Obstacle
Two Lovers face an Obstacle together.
29. An Enemy Loved
Required Elements : a Lover; the Beloved Enemy; the Hater
The allied Lover and Hater have diametrically opposed attitudes towards the Beloved Enemy.
Required Elements : an Ambitious Person; a Thing Coveted; an Adversary
The Ambitious Person seeks the Thing Coveted and is opposed by the Adversary.
31. Conflict with a God
Required Elements : a Mortal; an Immortal
The Mortal and the Immortal enter a conflict.
32. Mistaken Jealousy
Required Elements : a Jealous One; an Object of whose Possession He is Jealous; a Supposed Accomplice; a Cause or an Author of the Mistake
The Jealous One falls victim to the Cause or the Author of the Mistake and becomes jealous of the Object and becomes conflicted with the Supposed Accomplice.
33. Erroneous Judgement
Required Elements : a Mistaken One; a Victim of the Mistake; a Cause or Author of the Mistake; the Guilty One
The Mistaken One falls victim to the Cause or the Author of the Mistake and passes judgement against the Victim of the Mistake, when it should be passed against the Guilty One instead.
Required Elements : a Culprit; a Victim or the Sin; an Interrogator
The Culprit wrongs the Victim or commits the Sin, and is at odds with the Interrogator who seeks to understand the situation.
35. Recovery of a Lost One
Required Elements : a Seeker; the One Found
The Seeker finds the One Found.
36. Loss of Loved On
Required Elements : a Kinsman Slain; a Kinsman Spectator; an Executioner
The killing of the Kinsman Slain by the Executioner is witnessed by the Kinsman Spectator.