Prefacing this with: anything Eugenides does, ever.
Gen taking on the whole Queen's Guard and winning. Even when one of them turned out to be trying to kill him, he hardly thought of him as a threat at all!
The following exchange. And even better is the attendants' reactions.
Attolia: Ninety-eight days. You said it would take six months.
Euginides: I like to give myself a margin when I can.
The entire first book is revealed as one for Gen. Not only has he managed to retrieve Hamiathes' gift for his cousin, the Queen of Eddis, but it's revealed that the entire book was his plan to make sure Eddis wouldn't have to marry Sounis. Even better, it becomes clear on rereading that he has never once outright lied.