During the time spent in MLP fandom I met the idea of "Elements of Disharmony" for several times. And always they were too similar to their opposites. I mean, why the powers that want to destroy a society and represent various vices will cooperate with each other? Why they, being totally chaotic and destructive, will have any constant avatar, especialy a simple mortal creature? Seriously, I've seen Trixie as one of them in some theory. Now let's delve it the grim darkness of the lands beyond Equestria, where you can find at least pirates, conquerors and slave trade.
Soooo, I think you will guess the origin of this concept. The place where these… powers dwell we know as realm of dreams, which seems to be actually a realm, from where Luna's inner demon tried to escape into reality and where, I suppose, Twilight was alicornized. The second thing is that they more ideas than true gods with names, biographies and other stuff. And this is where they are similar to what we know: things like Tree of Harmony and Crystal Heart took their form just because of their nature, while our evil — as I said — can't.
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Lie is a god of intrigues, illusions and aspirations. It has many persons and names under which it manifests itself to the material world, weaving its intricate plans and concluding all kinds of contracts. Unlike Greed, invariably fair in the announcement of the price and operating with simple and clear things, Lie pathologically seeks to deceive the partner and prefers to work in muddy and abstract spheres, offering good luck, inspiration and even a creative gift entirely. And with all the desire to control and manipulate, it's just boring to play with the stupid and submissive, so the true blessing of this fickle god is awarded to those who are diligently trying to win his own game, and it is a victory, albeit fleeting and insignificant, that serves them as a reward.
Among these champions there are many kinds of sorcerers who are looking for a way to deceive their own nature and get not given them by origin strength and power. They written the most well-known black magic tomes, regardless of what they contain — the ambitions and interests of the witches affect the entire Pantheon and sometimes go even further. One such book was kept in the old castle of the princesses in the Everfree forest, and distinctive sign of the impact of the Lie is the fact that the formula of the transaction, the price of which was the excessiveness of the gift, was tied to the recognition of the goal that each who utters a spell no doubt wishes to keep secret.