In the novella The Strange Case of Dr. Jekyll and Mr. Hyde, there are quite a few instances of dialogue author Robert Louis Stevenson uses to show us that Dr. Jekyll and Mr. Hyde are two different people yet also the same person.
One of the best examples can be seen the first moment Mr. Utterson, Dr. Jekyll's lawyer, converses with Mr. Hyde. The novella opens with Mr. Enfield sharing a story with Mr. Utterson of Mr. Hyde being seen trampling a child and then agreeing to pay the child's family monetary compensation. After hearing the story, Mr. Utterson felt a strong urge to see Mr. Hyde. The reason behind his strong urge concerns the fact that Dr. Jekyll left in his possession a very strange will stating that, in the event of Dr. Jekyll's death, Dr. Jekyll would leave all of his possessions to Mr. Hyde, but if Dr. Jekyll should disappear, then Mr. Hyde should take the place of Dr. Jekyll. Hearing that Mr. Hyde is a morally questionable person, even a monster, Mr. Utterson becomes very anxious to see what Mr. Hyde is like for himself.
The next evening, Mr. Utterson sees Mr. Hyde about to let himself into Mr. Jekyll's home and approaches him, saying, "I see you are going in ... I am an old friend of Dr. Jekyll's" (Part I). Mr. Hyde's simple response to this statement shows us that he considers himself to be a separate person from Dr. Jekyll: "You will not find Dr. Jekyll; he is from home" (Part I). Mr. Hyde's response would have been impossible if he had thought of himself and Dr. Jekyll as the same person, because surely Mr. Hyde, who is Mr. Jekyll, has just arrived at home.
But Mr. Hyde also next says something that shows the reader Mr. Hyde also understands that he and Dr. Jekyll are deeply connected, so connected that Mr. Hyde knows what Dr. Jekyll has done and would do. The connection is shown when Mr. Hyde asks how Mr. Utterson knew of Mr. Hyde's name. Mr. Utterson evasively replies, "We have common friends," and suggests Dr. Jekyll as their common friend (Part I). However, Mr. Hyde's response to Mr. Utterson's reply is to grow angry and say, "He never told you ... I did not think you would have lied," showing us just how connected Mr. Hyde is to Dr. Jekyll (Part I).
Stevenson's use of dialogue to show the reader both the separateness and the connection between the two characters helps serve to foreshadow future revelations. Hence, by the time the reader hears Dr. Jekyll confess that, though they look and behave very differently, he and Mr. Hyde are two sides of the same coin, the "good" side and the "evil" side, the reader is not that surprised due to the foreshadowing clues.