I chose them too. I think they might have been adopted by Leaf Eaters but turned on them as they got older. It would explain why they know Leaf Eater, never use the Sharptooth language to talk to each other, and also why they aren't with their own kinds.
I villain worshipped those two when I was younger.
I almost was going to have the Land of Mists be a place for Sharpteeth that don't fit in anywhere else. (And where they hide both from other Sharpteeth as well as Leaf Eaters who might be after them.)