Rosencrantz and Guildenstern are not major characters, but they are recognizable from other guards and players in the play. They are referred as Hamlet’s school friends, and they come to Elsinore to talk Hamlet out of his supposedly crazy mind after his father King Hamlet’s death. After the talk between them and Hamlet, we see Rosencrantz and Guildenstern in spy position against Hamlet. They become the errand boys of Claudius and Gertrude, and report Hamlet’s actions.
Possibly, these two character’s vitality is their mission in the play. After Claudius’s conviction of Hamlet’s state of madness and his hatred towards himself, Claudius orders Rosencrantz and Guildenstern to take Hamlet and a letter which is a letter to King of England asking for the murder of Hamlet. This important mission and Hamlet’s possible fall in the play is directly connected to these two characters. Unfortunately, Hamlet realizes the plan and lets them die (or kills them) and they tragically fall in the hands of pirates.
In narrative means, Rosencrantz and Guildenstern are generally used to connect the parts of the story, as where Gertrude asks them to talk to Hamlet and fetch him, or Claudius orders them to take Hamlet to death.