It's clear that Caius isn't the only one who's been sent by his master. Caius is furious that he's being treated like a second-class citizen. He wants to stab Caius in the guts. He's going to use his heart to make Caius's tongue grow back. He doesn't want Caius to know that he was sent by Caius, because Caius can't possibly be a lower-class person. He also wants to know why Caius didn't let Caius go outside to get the anesthetic