It strengthens the connection between the two lines.
Answer: Vladimir - One of the two main characters of the play. Estragon calls him Didi, and the boy addresses him as Mr. Albert. He seems to be the more responsible and mature of the two main characters.
Estragon - The second of the two main characters. Vladimir calls him Gogo. He seems weak and helpless, always looking for Vladimir's protection. He also has a poor memory, as Vladimir has to remind him in the second act of the events that happened the previous night.
Explanation:
