According to their plans, Nathan is leading them the way inside the temple, through the back door of the temple. Throughout the path, he made sure to check upon everyone, making himself sure, whether the drug is really playing it's role or were they acting to fool them.
Well, they already got fooled by this little princess, who came bragging all the way that she is here with her brother, because of which, they needed to be extra cautious and had many back up men, as they thought special knights from Rutz house may join in this fight, making it hectic on their end.
So, he began to doubt whether they were drugged for real or not, as he couldn't totally trust that old man, even though they held ladies in his family as hostages. After all, that old man is also a citizen of this seazle empire, then how can black pawns totally trust someone of their enemy's place? Only a fool would.