Arachnid. Perhaps the most feared name in all of Equestria. An assassin of renowned infamy, Arachnid never failed to complete a contract killing. Anyone or anything unfortunate enough to become his target would be dead before the next sunrise, with proof of his success in hoof. Be it the severed ear of a haughty noble, or the freshly skinned flank of some wannabe criminal, Arachnid always delivered.
He was the stallion who made ponies fear to tread the streets at night, and even made Princess Celestia wary of the shadows. But at the height of his career, he vanished off the face of the planet. Never to be heard from ever again. Some speculated that he cashed out when the going was good and retired to live a long and happy life. Others say he went on to bigger and better things whilst hiding completely in plain sight.
While these explanation seem plausible, none mention even once about the legacy that he left behind. A legacy that he bestowed to his only kin and heir to his name. His daughter, Fluttershy.
One shot, not sure if I'm gonna expand on this