The OT3 solution is very reasonable and I agree that the ending suggests it! But unfortunately Aymar/Avoye didn't work for me because of the incest vibes--not that they're cousins, but the way they grew up together as children. And it leans into that, too! Oh well.

But anyway, the het is not what anyone reads this book for. Isn't Laurent's duel adorable? Awww. "Adorable" is not usually a word I'd apply to duels, but...