How did a second actor increase dialogue and dramatic tension in Greek tragedy?

Before Aeschylus, Greek drama was limited to a single actor who could only engage in dialogue with the chorus, resulting in a largely static performance.1

By introducing a second actor, known as the deuteragonist, Aeschylus fundamentally transformed the medium. This innovation allowed the two actors to converse directly with one another, which significantly increased the possibilities for dramatic tension and dialogue. This change shifted the focus of the performance, as Aeschylus reduced the role of the chorus and made the plot the central element of the tragedy.1

Ultimately, the addition of a second actor provided greater freedom in plot construction and allowed for more complex interactions between characters, laying the foundation for the aesthetics of drama for centuries to come.12