How would you act around him?

There's a local celebrity going to an event next weekend. He was at another event yesterday, and one of the attendees said that he'd had a really hard summer, so he wasn't his usual overly happy self. Like you could tell that he's upset. I'm one of his handlers, so that means I'm going to have to spend quite a bit of time with him. And I'm not entirely sure how I should act around him? Usually I get pretty psyched and go "OMG OMG I'M WITH _____" and they seem to get a kick outta that, but how should I act with this one?