The Vault Dweller. The Chosen One. The Lone Wanderer. The Courier. The Sole Survivor.
What do the most deadly and influential people in the post-apocalyptic remains of the defunct United States of America have in common, besides being human and living in the same Universe, albeit at different times?
Why, they're being brought into Equestria by a veteran time-traveler!
(A Fallout Series/My Little Pony Crossover)