He is known by many titles. Three Dog calls him 'Mr. 101', some call him 'The Messiah', his fellow Brotherhood members calls him a Paladin, but to all, he is known as the 'Lone Wanderer'. He help destroy the Enclave and it's remnants, help free the slaves from both the Pitt and Paradise Falls, took control over an Alien Mothership with survivors, and more than he can even listed.
But now though, after stumbling through some portal, is now trapped in a world known as Equestria with only the gear on his back and wrist.
(It's Fallout 3, but with Fallout 4 style. Also, MLP characters will be humanized, but have their abilities. Like the Pegusi will still have their wings, Unicorns, while not having horns, still uses magic, etc)
(NOTE: I do NOT own either. MLP is own by Hasbro and the Fallout Franchise is own by Bethesda)