Sanzo kept as still and quiet as he could as Drake worked. He wanted to hide his pain completely, so Cassian would have no reason to look down on him other than the fact that Sanzo was literally on the ground. He totally wasn't in severe pain, look, he barely winced! There was some wearing but otherwise he was a good patient. For him.

When Amberdrake mentioned the buckshot he muttered something unintelligible, undoubtedly something scathing about Cassian. This was all totally Cassian's fault. Sanzo picked a fight, sure, but Cassian was here eating people! How was Sanzo to resist that bait?

He felt mildly guilty, but only Drake could tell that.