Image imported from derpibooru 
Original Description:
 
After Luna transformed into nightmare moon, she used her powers to transform her most loyal followers into creatures better suited to a life in the shadows. While there were only a few hundred of these ‘Children of the Night’ at first, the transformative magic that flowed within them could be passed from one pony to the next, usually through an exchange of blood. Luna’s war with her sister lasted nearly 20 years, and during that time, the number of transformed ponies multiplied several times over. Before Celestia’s ‘intervention’ there were several thousand Batponies, Moonicorns, and Thrace ponies living in Equestria. Each herd was given different gifts to better survive and serve in the eternal night.
 
Batponies:  
-Their feathered wings were replaced with bat wings, mostly for the aesthetic.  
-The naturally omnivorous diet of a pegasus, which consisted of mostly plants supplemented with meat, was completely switched to be primarily meat with some plant matter.  
-The militaristic ways of pegasus society were well suited to the new regime of Nightmare Moon, and they served as her guards and eyes in the sky.
 
Thrace Ponies:  
-Thrace ponies, or wereponies in more rural regions, are the most dangerous of Luna’s creations.  
-Their normally vegetarian diets were replaced entirely with ones of meat. Thrace ponies are ruthless carnivores, and their strength and speed make them formidable predators.  
-Thrace ponies served in Luna’s army, forming a great legion of ruthless warriors to fight for the lunar cause.
 
Moonicorns:  
-Moonicorns are the least changed of all of Luna’s creations, with their only change being their ability to digest blood.  
-While the other ponies transformed by Luna were made carnivorous, moonicorns specifically require blood to survive. Moonicorns can also pass on their powers to others when they feed, and all ponies turned in this way will have moonicorn traits regardless of their herd. (i.e. an earth pony that was drank from would not become a true thrace pony, and would simply have vampirism, the same goes for pegasai)  
-Moonicorns served in Luna’s court, and were often sent into Equestrian society to pass on the message of lunar superiority.
 
All Lunar Creations:  
-Slitted, catlike pupils. Their eyes reflect light at night and can be seen peering out from the darkness  
-Require animal blood and/or meat to survive. their carnivorous diet was to better survive in a world where sunlight to grow crops was scarce, and eating other animals was more efficient and accessible.  
-Their ears lack the thick inner fur of their non-transformed cousins. The lack of fur allows for better hearing, and the tufts of fur on the ear tips draw in sound and are considered attractive.
 
After the war, and Luna had been banished to the moon, Celestia was unsure of what to do with all these magically transformed ponies. After much deliberation and discussion with her court, a difficult decision was made. For the safety of Equestria, all Thrace ponies would be rounded up and executed. Batponies and Moonicorns were shunned from society, and were often chased out of their home ranges and forced to flee to the very fringes of the empire. Some say that a few Thrace ponies survived, and that their descendants live deep in the Everfree, though no official sources can confirm this. Today, Luna’s creations have been welcomed back into society, and Celestia has issued a formal apology for her actions, though many refuse to accept it. Occasionally Thrace pony spottings will be reported, but they are usually just normal Terrans who have been infected with vampirism.
 
Notable Figures who are descended from the Lunar Legion:
 
-Twilight Sparkle: her father is half moonicorn, and has passed some traits onto his daughter and son.  
-Fluttershy: she contracted vampirism from a bat who carried batpony blood in their body. She is not classified as a batpony, and is technically a vampire pegasus.  
-Tempest shadow: Both her parents were Moonicorns, she can trace her family lineage back to the noble moonicorn houses of old.  
-Vinyl Scratch: while she was born a normal unicorn, she contracted vampirism as a teenager and made her transformed state part of her brand as a musician