Two reasons occur immediately; One - they provide a force of opposition against which the protagonist can be tested, someone to oppose their desire and their hero's journey. Two - they provide a contrasting character to the protagonist - they are what the protagonist isn't, or what he fears he could be, or his darker self writ large. They are what he might turn out to be if his journey of self-discovery goes wrong.

Heed the call? I'll finish the first draft next week. I'm a true git.

Nemeses is where all the fun is, the friction in the fray, the dark yin to hero's bright yang. And nemeses having fun is very best of all. Great example is Allan Ryckman (Hans Gruber, Sheriff of Nottingham). So could a story about all nemeses be fun? Tonight I find out, with as close as it gets,13 Assassins, can't wait.

It can be helpful to think of the Nemesis as a 'shadow' figure in relation to the Protagonist, basically a projection of the Protagonist's worst fears. Once again with Silence of the Lambs [which may be THE perfect script in terms of character archetypes]. Clarice's Disunity all began when her father was murdered -- an innocent lamb if you will. Hence her connection to the lamb she tried to save on her uncle's farm in Montana. So she has this 'boogeyman' haunting her, these murderers of her father. Yet she puts herself in a position to catch some 'bad guys,' drawn to the task both consciously and unconsciously to do something to assuage the guilt she feels about her father's death. So along comes Buffalo Bill, who represents everything symbolically and psychologically Clarice has going on with her shadow. While this is a challenge, of course, it also sets her on a path to vanquish her shadow. Thus as you develop your Nemesis character, think about how they are tied to your Protagonist, especially on a psychological level. You may find riches there.

According to the Oxford Dictionary, a nemesis is the "inescapable agent of someone or something's downfall" which could be "a long-standing rival; an archenemy, a downfall, or retributive justice." In classical mythology Nemesis was the the goddess of retribution or vengeance. Thus nemesis has come to mean the agent of retribution or punishment. For me 'nemesis' doesn't equate to the idea of antagonist. An antagonist is the character who wants to prevent the Protagonist from reaching the goal. He may be, such as the case of the Sheriff of Nottingham, one filled with goals of punishment in order to extract the power he wants, but not every antagonist has that ideology. The forces of antagonism are what really matter in the process of character development. In a story such as Pirates of the Caribbean, Will Turner's development as a character depends on the way the forces of antagonism shape him. The true antagonist is the British Government, in the first episode manifested in Norrington, in the subsequent two, Beckett and the East India Company. Turner's desire for the heart of Elizabeth Swan is contested by Norrington, but the true goal of the story, the truth about his origins and his father and therefore his true character and the treasure that lies in its discovery, is contested by Norrington and his naval Forces. It is true that Norrington, as agent for the British Govenrment, wants to visit punishment and retribution upon Turner, thus making him a nemesis character, but nemesis, for me at least, doesn't reach quite far enough into opposition as the story calls for. Antagonism calls for more opposition than nemesis describes. In a romance, where the object is to bring two lovers together, the two characters are in opposition, thus Protagonist and Antagonist, but rarely is the Antagonist character motivated by punishment or retribution. Quite often the payoff in a story is to see the Antagonist get his 'just deserts' as the protagonist rises the claim the keys of the kingdom. In many ways, the retributive justice is delivered by the Protagonist's actions. The more poetic this final justice is, the more we attribute it to the Protagonist's goal. So a nemesis character, for me at least, is sometimes called for, possibly works best in thrillers and crime stories, but perhaps also horror and fantasy, where the villain is hell-bent on causing pain and suffering, but not always. It is often shadowy, but perhaps not as shadowy as the antagonist character, but it is also often a manifestation of the protagonist character. Important, yes, sometimes, but not as character shaping as the Antagonist, who needs to be more than 'nemesis'.