“Tell me if you need me to stop,” Shang Beida demands. It’s patently obvious how incredibly uncomfortable with this Casper is, every line of his body tense, but… they both don’t want bits of plant inside him, and that isn’t going to go away by wishing. He braces a careful hand on his boyfriend’s arm, grits his teeth, and starts picking out fragments of bark, flinching a little when the wounds he’s cleaning start bleeding afresh. Casper wasn’t kidding about his blood being lighter than ordinary human blood. He tries to focus on that and on his task rather than on which one of them might be trembling.