So,according to the book, Dragons: A natural history these serpentine dragons were so fearsome mostly due to it's extra toxic venomous breath(which all sea serpents had bad breath but the Guivre was extremely toxic) but a perculiar trait of this dragon is it's sense of modesty. As legends go, a young farmer was taking a dip in the ocean to cool off after a day's hard work(not clothed as one would be when swimwear wasn't a thing) when suddenly a guivre appeared out of the bushes looking ready to eat him whole. But then it stopped,Recoiled as it hit then averted it's eyes while blusing before getting out of that embarrasing situation(1) Honestly, why does a evil dragon have such a respectable sense of modesty? like what were the french thinking?