Chronicles of Ascension
The largest thing to darken the Ninth World sky is the xi-drake, a massive, white-skinned reptile with broad wings, a long tail, and a large armored crest on its head. The creature is light for its size, and the crest has a unique organ that helps it to ﬂy (though no one knows precisely how it works). On land, wings folded tightly at their sides, they slither, helped along by small claws on their midwing joints and vestigial hind legs.
Xi-drakes have keen senses, but more impressively, they can read the mind of any intelligent living creature at long range and thus are almost impossible to deceive. They breed rarely but are extremely long-lived. Xi-drakes nest in mated pairs; otherwise, they travel the world alone or with a single rider/companion in pursuit of the xi-dragon equivalent of obligation and honor.
Xi-drakes are straightforward combatants, attacking with a bite or knocking opponents prone, but since they read minds so easily, they use this information to aid in their attacks and defense. They cannot speak (telepathically or otherwise), but their ability to read minds allows a sort of communication. They are not so much tamed and trained as they are befriended.
Due to a pact made more than a hundred years ago, xi-drakes serve as mounts for Angulan Knights. Once a xi-drake is bound with a rider/companion, the two work in concert until death (usually the death of the rider, since xi-drakes live for hundreds of years).