In my view, it would be the weak imperfection of mankind. Indeed, Rosencrantz and Guildenstern used to be Hamlet’s university mates and friends. However, the minute Claudius asks them to spy on Hamlet they accept without caring to question Claudius’ motives for such command. Hamlet discovers them very quickly and is deeply disgusted and disappointed by their sycophancy. The fact that they are plebian also reveals a very classist attitude of the author.
Indeed, they could be anyone low extraction in hamlet’s world. The scene two of act four is by far the one that best shows not only how both characters are interchangeable but also denied the initiative, by everyone else in the play. Rosencrantz, who interestingly uses the pronoun “us” for a demand that only he is uttering (lines 07, 22 & 11) is rhetorically suppressed very quickly by Prince Hamlet, who informs him that as the “son of a King he does not even listen to the demands of a foolish sponge” (lines 11 & 21).
Not only is Hamlet asserting his towering nobility over both of them; he is also denying them their personhood: a sponge is an object which does not move nor does it have a will of its own and as sponges, Rosencrantz and Guildenstern are only “kept” in suspension at the royal court for the use of others (line 15).
