An antagonist is a character or group of characters, or, sometimes an institution of a happening who represents the opposition against which the protagonist(s) must contend. In the classic style of story where in the action consists of a hero fighting a villain, the two can be regarded as protagonist and antagonist, respectively. Contrary to what some people commonly believe, the antagonist is not always the villain, but simply those who oppose the main character. More often, stories simply do not have characters that are readily identifiable as most heroic or villainous. Instead, the antagonist becomes that character, group, or metaphysical force which provides the chief obstruction or conflict to the protagonist(s) of the story.

In a SexSkit, there is always one protagonist and only one antagonist. The obstacle poised by the antagonist to the protagonist is usually a decision to accept the terms of the seduction as dictated by the rules of the genre and sub-genre, and progress into sexual activity with the antagonist. This creates the conflict in the SexSkit, and while internal, it helps to create the atmosphere and generate sexual tension between the participants. In the majority of the SexSkits, the protagonist will be the male participant, and the female participant will assume the role of the antagonist. There are times where the protagonist may switch roles with the antagonist, such is the case in sexSkits that are written around the "Turnabout" genre. The "foil", or conflict usually takes the form of perceived infidelity or some other moral issue, where the protagonist must choose to remain moral and the SexSkit ends, or succomb to temptation, and the SexSkit progresses to an eventual sexual union and climax.