When Zach had seen Rosier as a patient all of one time, it had been creepy as hell, to him. But whether that was Rosier actually being creepy or Zach just being nervous, Zach didn't know. He trusted Theo's judgment that Rosier was a good healer, and obviously Zach liked living (so that if he somehow needed Rosier's help to stay alive, then fine, okay). But he still didn't want to go to Rosier for anything Theo was capable of. Even if Rosier did it better.
"I haven't talked with him enough to really get along or not," Zach mentally shuddered at the idea, "But I don't really want to find out." Not when Rosier did things with his charm and was all...making Zach's head go places Zach didn't want it to go.