Evil twin

The evil twin is an antagonist found in many different fictional genres. They are physical copies of protagonists, but with radically inverted moralities. In filmed entertainment, they can have obvious physical differences with the protagonist—such as facial hair (often a goatee), eyepatches, scars or distinctive clothing—that make it easy for the audience to visually identify the two characters. Sometimes, however, the physical differences between the characters will be minimized, so as to confuse the audience. Both roles are almost always played by either the same actor or the actor's actual twin (if the actor has one).

Though there may be moral disparity between actual biological twins, the term is more often a misnomer. In many cases, the two look-alikes are not actually twins, but rather physical duplicates produced by other phenomena (e.g. alternate universes). In others, the so-called "evil" twin is more precisely a dual opposite to their "good" counterpart, possessing at least some commonality with the value system of the protagonist.

The concept of evil twins is ancient and mythical. One of the earliest may be in the Zurvanite branch of Zoroastrianism. This sect distilled the general abstract duality of Zoroastrianism into a concept of manifest twins "born" of a monist (first) principle Zurvan "Time." In this cosmological model, the twins — Ahura Mazda (Ormuzd) and Angra Mainyu (Ahriman) — were co-eternal representatives of good and evil. Ahura Mazda, representing good, was eventually expected to win the battle. The doctrinal foundation of Zurvanism lies in its interpretation of the Zoroastrian precepts of Free Will: Like Mazdaism (the other, and still extant branch of Zoroastrianism), Zurvanism emphasized that mortals always "have a choice between good and evil, and that one is always free to make the choice one way or the other." Zurvanism took this one step further and considered Angra Mainyu "evil" by choice, rather than by nature. This characterization is important to modern uses of the "evil twin", as most examples are in fact opposites of their "good twin", rather than wholly evil.

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