A dramatic monologue is a long piece of writing or poetry that seeks to reveal the reader or character’s innermost thoughts and feelings. Dramatic monologues can be entire works on their own, such as Tennyson’s poem "Ulysses," or they can simply be passages within a longer work, such as the soliloquys in Shakespeare’s plays. The dramatic monologue as a form or literary device was popularized by English Romantic poets such as Percy B. Shelley and Robert Browning.
Form
The dramatic monologue can take a variety of forms and can be strictly structured, such as one that follows the form of a sonnet, or can be loosely structured, as a piece of prose. They are written in the first person and always have a defined audience in mind. The reader of a dramatic monologue takes the position of the silent listener.
Character
The character in the dramatic monologue is revealed through the revelation of his innermost thoughts. The dramatic monologue often takes the form of a confessional or is the soul or conscience of the character. The character reveals thoughts and feelings that are hidden to others --- thoughts that would not be reveled except through this almost private missive to the reader or audience.
Revelation
There is usually a dramatic revelation of some note in a dramatic monologue. The device is often used to impart some great insight or attitude that makes the monologue truly "dramatic." The soliloquy of Lady Macbeth in Shakespeare’s "Macbeth" is a good example. In the scene in which she reads a letter to herself, she then begins a soliloquy that reveals her innermost thoughts and feelings and contains dramatic revelations that advance the plot.
Climax
Most dramatic monologues build steadily toward a dramatic climax, usually toward the end of the monologue. The preceding parts of the monologue should be used to set up and build toward the climax. The climax then should be revealed with all due drama. After the climax, the author should not linger too long in the aftermath because the audience, having experienced the dramatic high point of the dramatic monologue, now needs to focus its attention on new plot developments.