Director wishes or not, Percy had personal issue with this scene. It had been the moment where he had gone through the entire spectrum of emotions, where upon realizing Marguerite had never betrayed him, that her hand had been forced by Chauvelin, that he had wanted to embrace her, to tell her he was the Pimpernel, but he couldn't. Not then. Because the content of the scene wasn't about them. It was about saving Armand. But all the unspoken things, the actions, they were all about Percy realizing things. And Nate was having some difficulty conveying the unspoken parts.
After Nate's acceptance, Percy hopped up on stage. He wasn't a director or even an actor, but he had been around Marguerite enough to pick up on some of the intricacies of acting and scene interpretation. So while he was going to make an excellent showing of his "observations," he needed to word them just right so it wasn't as though he actually was Percy Blakeney.
"When Marguerite is revealing her past, I'm not getting the sense that it really effects Percy at all." Really, talking about himself in the third person in this matter was really strange. But he kept with it. "The way I see it from the audience, you're portraying more of the Pimpernel in this scene than Percy, and Percy does break the Pimpernel facade briefly." He managed to refrain from going so far as to say he'd nearly reached out to touch Marguerite at the point where he broke out of his Pimpernel disguise. "And with the fact Marguerite's back is to you, you should play more on the physical reactions so the audience can see the emotions playing across Percy. And that's what I want to see. This is the pivotal scene for Percy, the time when he realizes Marguerite never betrayed him, and that fact should register somehow with him."
Percy thought he was doing a very excellent job of keeping his comments to an audience member's perspective only. "This is also the scene where you have the unique chance to show how diverse Percy truly is. He isn't just the serious Pimpernel or the silly aristocrat. He is intelligent and emotional, and this is the scene where he breaks that silly British notion of 'keep calm and carry on.' Really, just let go of your restraints. Actually here, perhaps a demonstration?" Though Percy didn't exactly wait for a response. His eyes were already looking for Marguerite off-stage. When he located her, he marched over to her and grabbed her wrist, not bothering to say anything, and just pulled her out on stage. Because clearly a demonstration was needed.
Or Percy was just insane. Either would be accurate, no doubt.