Rosencrantz and Guildenstern Are Dead
Ros is Guil's sidekick, if only because he sees himself that way. Guil never appears without Ros until the very end of the play, and Ros is the one who leans (sort of) toward Guil's little philosophical discourses and indulges him in word games. The two are inseparable, and it has been suggested that in a sense they are just two different halves of the same personality. If you look at the many instances of repetition in the play, you'll find that Ros and Guil often influence the way the other one acts, even if it's not acknowledged.