Oh yes, I noticed in her brackets she was essentially going hmmm at him a bit there. Gray's onto him... Were he harmonized I think it'd be overtly obvious since his eyes can turn amber. He and Kamui seem to be able to go a very long time without blood, but he could very easily say something that tips her off. Subaru's very much not about the hurting/killing without necessity life and he knows vampires don't need to so...small angry pureblood vampire for Gray to observe.

He quite probably hasn't fed in some time, but you know. High level of control on this little guy.