Parents: Luna, Sombra  
Species: Unicorn / Umbrum hybrid  
Special talent: Battle Defense/Strategy  
Occupation(s): Captain of the Lunar Guard, Prince of the Night, Aristocrat, Canterlot Bachelor  
Nickname(s)/Alias(es): Pyrie (by Marina and his sisters), Pyre (by his mother and father), Riri (by Sundrop only), Py (by most friends, started by Sunset), My Prince/Lord/Highness (by subjects and other aristocrats)
 
After Sombra was reformed and he and Luna married, they ended up sharing some very interesting news with Celestia - Luna was going to have a child. They decided to keep it under wraps for fear of what an alicorn/umbrum hybrid would look like and they were right to do so. Their child was born looking horrifyingly starved and sick. Panicked and heartbroken, Luna had several revered doctors do examinations on the wee foal only to find… absolutely nothing wrong. He was reported to be perfectly healthy by every single doctor. His Umbrum heritage simply made him appear deathly ill.
 
Worried that others would reject him for his appearance, Pyrinos was kept away from other ponies with only a select handful of bat pony guards to keep watch on him and unicorn servants being allowed near to help care for him. All were sworn to secrecy of Pyrinos’ appearance and were supposed to claim that the young prince was simply sickly and bedridden.
 
However, there were two ponies who stood out from the rest - a bat pony guard by the name of Shakti and a unicorn named Selene Star. Neither of these ponies ever looked at Pyrinos with anything besides warmth and acceptance, and thus they became closer to the prince than all others. Shakti, or “Shade” as young pyrinos dubbed her when he couldn’t quite pronounce her name, was assigned as his personal body guard. Selene was brought in as a nanny and eventually became his magic tutor. With permission from the princesses, she successfully taught him a spell to disguise his umbrum appearance and make him look like an normal unicorn so that he could stop being hidden away from the world.
 
With that one spell, he was freed from his solitude and went on to become a favored bachelor amongst aristocrats and lower class ponies alike, and eventually worked his way through the Lunar Guard until he became Captain.