Can I use OOC information? Because he's an OC it's probably going to be hard to figure out what is and isn't obvious, so ask me if there's something from his history you'd like her to notice.
Is there anything in particular you would like Shirley to notice? Possibly that he gets all twitchy when magic comes up and specifically that he used to be a mage, though this might not be obvious for a long time. He does come off as someone who's hiding something.
Is there anything you specifically don't want her to notice? Nope