Board Thread:Lore Discussion/@comment-2165692-20161018043733/@comment-2165692-20161109172534

The Blades might know him, just never mentioned him. They mentioned Paarthurnax because they know the Dragonborn has met him, without killing him.

As for Numinex, there's already huge threads on that subject, they should be able to explain that to you.

Papré is unlikely to even be a Dragon. He might be another creature entirely. Such as Dragonlings.