I didn't fully understand the chapter till I read the comments, but I could tell by the facial expressions of the princess that our MC was asking the right questions and giving smart answers. While the bodyguard is looking for obvious signs of valor and leadership, the princess is looking for signs of someone with a keen mind, quick wit, and a silver tongue.
Also, I'm liking how the MC seems like an actual person in this story. He's not overpowered. He's not weak. He has his strengths and weaknesses. His personality is on the passive side, but honestly, given why he's there, that's more of a positive trait than a negative one.