What: Making dialogue shift the balance of power between characters, not merely convey information.
Why: Living dialogue is a small conflict; each reply gains or loses ground, gripping the reader.
How: Before each line ask: what does the speaker want from the other now? And let the reply resist or evade.
Common mistake: 'Info-dump dialogue' where characters explain to the reader what they already know.
Exercise: Write a scene where one character tries to persuade another, each reply changing who holds control.