A subsidiary character who emphasizes the traits of a main character.

Foreshadowing or adumbrating is a literary device in which an author hints certain plot developments that perhaps will come to be later in the story.

Form is the shape, visual appearance, constitution or configuration of an object.

 An essay is a specific format to present your side of an argument. 

The field of formal language theory studies primarily the purely syntactical aspects of such languages—that is, their internal structural patterns.

A frame story is a literary technique that sometimes serves as a companion piece to a story within a story, whereby an introductory or main narrative is presented, at least in part, for the purpose of setting the stage either for a more emphasized second narrative or for a set of shorter stories.

Free verse is an open of poetry. It does not use consistent meter patterns, rhyme, or any other musical pattern. It thus tends to follow the rhythm of natural speech.