meet Damian an immortal Bat, Alicorn and Demon pony crossbreed/hybrid  
This is Damian’s “normal” form. He has and other form but he don’t show it often.
 
He has the eyes and horn of a demon pony (Kivali’s species)  
Also Demon ponies don’t have cutie marks so he doesn’t have it either.
 
Many see him as scary and mysterious because of his looks and how he acts at times.  
Damian acts as a gentleman most of his time awake, but he has moments of coldness too.  
but he basically live in the canterlot library at night, reading/studying/learning about magic and pony history.
 
Many ponies calls him “The Dusk Rose Prince”