Dark Aether is unicorn, doctor and cleric of Luna, currently employed at the divine services wing of Ponyville hospital. He is also a member of the local Ordinum Aurora. Following the recent events in Ponyville that brought him nose-to-nose with competent fighters from across Equestria (Shadow and Silver, Other characters in group A), Dark Aether is committed to the destruction of the evil forces plaguing Ponyville, and possibly all of Equestria itself.
Dark Aether was born to a wealthy family around 30 years ago in the now city-state of Canterlot. Always dedicated to aiding his friends and companions, he earned his Cutie Mark, a star-stricken cross, after using his magic to stabilise an injured friend, following an ill-fated excursion into the surrounding forests. From then on, Dark Aether dedicated his life to finding ways to use his magic in a healing context. Enamoured with the opportunities for peace and quiet introspection that night provided him, Aether associated himself with the divine magic of Princess Luna - pushing his studies into medecine and divine magic further and further. After learning of the ascension of Twilight Sparkle, he decides to do all in his power to join the Ordinum Aurora, in order to comprehend the processes behind such miracles - as well as use his magic not only to heal patients, but possibly get an insight into what affliction seems to be ravaging Equestria.
The near-devastation of Canterlot by a violent earthquake pushes Dark Aether to seek refuge somewhere violence and disaster are kept at bay; he decides on Ponyville - joining the local Ordinum Aurora, and eventually founding a divine services wing at the local hospital. Feeling that he has finally found his place, Dark Aether settles in, and a few years later, has become complacent... preferring to avoid conflict of any sort, he is content with his post and fulfils his ambitions by doing the best for his patients.
When Pinkie Pie disappears from Ponyville, cryptically annnouncing the end of her days of laughter, Dark Aether is perturbed... reminded of the the Taint's corruption of the world around hin, a desire to bring back Good to homeland begins to grow within him. After a surprise attack on Ponyville, and the offer by the Equestrian Crusade to investigate the events surrounding the mysterious attack on the town, his ambitions for restoration seem to be ripe for fulfilment...