Actant
In narrative theory, actant is a term from the actantial model of semiotic analysis of narratives. The term also has uses in linguistics, sociology, computer programming theory, and astrology. In narratology. Algirdas Julien Greimas (1917–1992), professor of semiotics, is widely credited with producing the actantial model in 1966. This model reveals the structural roles typically performed in story telling; such as "hero, villain (opponent of hero), object (of quest), helper (of hero) and sender (who initiates the quest)." Each of these roles fulfills an integral component of the story, or, narrative. Without the contribution of each actant, the story  may be incomplete. Thus, an "actant" is not simply a character in a story, but an integral structural element upon which the narrative revolves. An actant can also be described as a binary opposition pairing, such as a hero paired with a villain, a dragon paired with a dragon-slaying sword, a helper paired with an opponent. Actantial relationships are therefore incredibly useful in generating problems within a narrative that have to be overcome, providing contrast, or in defining an antagonistic force within the narrative. However, the same character can simultaneously have a different actant (or way of concern) in  regard to a different sequence of action, event, or episode in the story. Therefore, it should be distinguished from a character's consistent role in the story like the archetype of a character. The concept of actant is important in structuralism of narratology to regard each situation as the minimum independent unit of story. As defined by Julia Kristeva. In 1969, Julia Kristeva also attempted to understand the dynamic development of the situations in narratives with Greimas's actantial model. She thought the subject and the object can exchange positions, and accordingly the supporter and the opponent can exchange positions  too. Furthermore, the pair of subject and object sometimes exchanges its position with the pair of supporter and opponent. There are, however, multiple overlapping situations in narrative at a given time. To contend with the overlapping situations present in all narrative structure, she called the potential actant shifts not "change", but "transformation." This should not be confused with Greimas's own transformational model, another narratological framework. As defined by Vladimir Propp. Independently, researching Russian folklores, Vladimir Propp also provided the "7 act spheres": However, these are not the types of the person in the story, but rather patterns of behavior : the same person may sometimes act as one "sphere", and at other times as a different "sphere". In linguistics. Linguist Lucien Tesnière considered the function of a verb as most important in dependency grammar and invented the term "actant", various persons that accompany a verb: This concept of actant is similar to that of argument. Algirdas Julien Greimas redefined actants as the 3 pairs "Modulations": In sociology. In sociology, the semiotic term "actant" was incorporated into the actor-network theory by Bruno Latour and Michel Callon, the activity of which is described as "mediation" or "translation". In astrology. Since ancient  times, astrology considered and analyzed the position of the persons concerning a situation with the symbols of the celestial objects and constellations. Georges Polti counted up the needed positions in his famous "The Thirty-Six Dramatic Situations". Étienne Souriau reduced them to only 6 positions named "dramaturgic functions" with astrological symbols: