Cadance is immortal. Her husband, however, is not. And what will she, the princess of love, be without her husband? As such, Cadance strikes a deal with the only pony who has truly cheated death: King Sombra.
What is legacy? Is it the memory you leave behind, the tangible deeds that can be seen and whose echoes ring throughout history? Is doing simply enough? Or must we be remembered to truly matter?
With King Sombra back in power and ruling over Equestria with an iron hoof, he has taken over the minds of so many ponies and now he has his eyes on a new slave.
Sombra finds himself looking for Spike after he and Twilight get into a fallout, then asks Spike why he was so upset at Twilight in the first place. He wasn't prepared the for the answer he received.
Fluttershy has always believed no situation is hopeless. When she meets an unfortunate orphaned unicorn foal, cursed with an evil shadow that haunts him, she might have just met somepony she can’t save.
Twilight has only narrowly managed to save herself and the Crystal Empire from Sombra… but after a brush with the forces of dark magic, she finds herself with a piece of his mind inside hers.
Side story to "The Not-So-Normal Adventures of King Sombra and Pinkie Pie". Pinkie reflects on her relationship with Sombra after she finds out he's been injured from Tirek's attack on the Golden Oaks Library.
After 1000 year of not knowing true love Sombra finds it in a unicorn filly named Lucina who is the youngest daughter of Princess Cadence and Shining Armor.