Rosencrantz and Guildenstern, long time school fellows of Hamlet. Hamlet's friends who would stand by him through thick and thin, or loyal subjects of a treacherous king that would turn on Hamlet at the drop of a hat. They are asked to the castle by the king and queen to find out what is troubling Hamlet. They are used by Claudius. And they bring Hamlet to his death.
Rosencrantz and Guildenstern make their first appearance in the play when they are summoned by the king and queen. They are long time friends of Hamlet, and because of this the king and queen believe that they can find out what is troubling Hamlet. When they first appear we see them as loyal subjects to the king and as caring friends of Hamlet. When they first speak to Hamlet in the play he tells them that "Denmark's a prison." Or rather it is to him because of his bad dreams. When asked why they are at Elsinore. They say, "To visit you, my lord; no other occasion." They do not tell Hamlet that they were sent for by the king, or that they are here to find out what troubles him. However Hamlet knows that they were sent for, and when he asks them directly they hesitate before they answer.
Rosencrantz and Guildenstern are used by the king. They betray the trust of Hamlet by working for the king in return for a hefty reward. Hamlet is no longer fooled by their false friendship. He sees them as enemies, as "adders fanged". It is at this point in the play that we see Rosencrantz and Guildenstern as loyal subjects as his majesty and not as friends of Hamlet. Hamlet describes them as, "[a sponge] that soaks up the King's countenance, his rewards, his authorities. But such officers do the King best service in the end. He keeps them, like an ape, in the corner of his jaw; first mouthed, to be last swallowed. When he needs what you have gleaned, it is but squeezing you and, sponge, you shall be dry again." Hamlet knows that they are loyal to the king and for this reason he keeps his "antic disposition" when he is around them.
In the final scenes with Rosencrantz and Guildenstern the king has them set off for England with Hamlet. Supposedly to get him away from Denmark after the killing of Polonius, but in actuality they are bringing him along with orders for his execution. This is the final proof that Rosencrantz and Guildenstern are devoted to the king and do not care about Hamlet. However, all turns out o.k. when Hamlet switches the letter with one he forged telling England to execute Rosencrantz and Guildenstern. He can do this with a clear conscience because he believes that they are guilty by association with Claudius.
Were Rosencrantz and Guildenstern Hamlet's friends, or were they merely pawns in Claudius' web of deceit? If they were truly Hamlet's friends and they wanted to help him they would have been honest from the beginning. However, perhaps they were just loyal subjects to the king and they did not know what they were doing was wrong. The truth is that Shakespeare is not very clear on the details of Rosencrantz and Guildenstern and we can never be entirely sure of what they were thinking.