I guess I read a lot of mysteries, so I pretty much suspected Percy when he and Marguerite came to the Inn. I suspected this because of the description of him, being tall, well built, etc., etc. And also, I caught on that he wasn't with Marguerite during the whole time of the visit of her brother. There seemed to be little things along in the book, that suggested that Percy was 'it': 1) his frequent absences with little or no explanation to Marguerite (is she really that dense?), 2) his all together 'too' lazy attitude, 3)How did he keep in such great physical shape if he was so lazy?, and 4) he was great friends with Sir Andrew and the other (I can't remember his name). I really enjoyed the book. I thought it was well written and, I thought, just a little predictable :)
At the Inn, I thought Sir Andrew and his cohort were a little lax in their duty, I mean, really, they can get people in and out of France with out getting caught, but they don't notice a guy climbing under the bench in the dining room, it really couldn't have been that big of a room! They should have been more vigilant.
I can't really decide if Marguerite was justified in her actions or not, considering I pretty much knew Percy was the SP from the start, so I wondered why she didn't also. However, I think Sarah has a good point, if she really didn't know, then yes, it's a no brainer to choose one's family over a stranger. She also had great respect for the SP so she was pretty sure he could get himself out of any danger, and once she knew, she did everything in her power to help him. So that's a point for her.
Now, I think that Percy was listening at the theater box door and knew exactly how he was betrayed, also there was something about the way he looked at Marguerite after he came in, as if waiting for her to tell him about the problem with her brother and hoping she would trust him with that information and when she didn't he thought he had lost.
There seems to have been several things Marguerite could have done differently in order to save her brother (but then we would have the book, if we went and changed everything!). 1) she could have confided in Percy, 2) told Sir Andrew about the plot instead of stealing his paper or 3) told the truth about herself in the very beginning and then she would have known all about him.
Which brings me to my question: Wasn't Percy just a little bit of a hypocrite? He seemed to not forgive Marguerite for not coming clean before they were married, yet he kept his secret from her and acted a totally different person than he really was. They should have trusted each other, but there again, it wouldn't be the book it is without those things. :)