Gatsby was accustomed to Mitchell's ways, and it was immediately apparent to him when Mitchell seemed to have a problem with a particular customer. Not that the vampire was particularly subtle about such things. He didn't pander to anyone, and it was something Gatsby greatly admired about him. He'd had more than enough of phonies to last him a lifetime.
He moved from cleaning the shelves to prop himself against the bar nearby, half-heartedly polishing an already clean glass. He wanted to keep near in case anything went down. He knew that Mitchell could handle himself, but that wasn't the point. Loyalty meant a great deal to him.