Hatchling: The pitch black egg falls apart to reveal a small, thin, black horse. The little horse lifts its head to look you in the eye and spreads out its large bat-like wings. It folds its wings to its side and walks over to you unsteadily. It wobbles and falls, looking startled. You chuckle and walk over to the small horse and gasp. It looks up at the nose and whinnies softly, blood red eyes looking sad. You lean over it and run your hand over its thin black pelt, wondering at the wings and the bones sticking through its skin. There's several alarm calls from other animals in the Keep. The foal looks up and hisses like a cat, revealing sharp dagger-like teeth. The Keep falls silent and it nods, then looks back at you and standing up, starts looking for food.
Adult: Your small awkward foal has grown up into a formidable and terrifying looking beast. Standing taller than the largest pegasus, the Thestral is a huge and powerful animal. You can easily ride it for days without it wearing out. It's still not entirely welcome in the Keep but it's indifferent to everyone else but you, and is an excellent companion.
General: Thestrals are rare and almost never seen. They live deep within the Silva Forest and it's nearly impossible for a Magi to take an egg, as the parents rarely ever leave the egg alone. On the rare chance that a Magi does get an egg, a Thestral raised in the Keep is a loyal companion. With their protruding bones, dagger-like teeth, and massive bat wings, Thestrals are often veiwed as omens of death.
grr, that's all i came up with, and i really don't like that ending *glares at it* anyway, tell meh what you think
oh, and this is what i think it would look like as an adult option one
![Image](http://images.elfwood.com/art/o/u/oulevay/skeleton_horse.jpg)
options two
![Image](http://www.cgw.com/images/Media/PublicationsArticle/pg14a.gif)