ASTRID was startled when he saw the duke who was striding in their direction. He couldn't read anything on the other's face. But the fact that he was probably planning to talk to him was a problem in itself.
Aside from the obvious reason that a noble duke taking the initiative to talk to a rookie actor could be seen as strange, it could also start some weird rumors. It's already giving him goosebumps, and not the good kind at that, just thinking of that possibility.
He actually wanted to pull Ellis away while the duke still hadn't made his way here. But he could be seen as rude if he did that. Not to mention, making him look more suspicious.
But thankfully, Casey seemed to be on the same page as him. Because he saw the other holding the duke's elbow, seemingly trying to stop him. Casey whispered something to the duke's ear and the latter completely stopped walking.