Applejack finds a strange visitor in her apple orchard one day, with even stranger stories to tell...
MLP/L4D2 crossover. My first story on FiMfiction.net! May add more tags as story progresses.
Credit for the image goes to brokencreation on DeviantArt.

Instead of being killed in the cold Antarctic by Dr. Manhattan, Rorschach finds himself rematerialized in a strange new, pony filled world. He finds himself drawn into the lives of the ponies of Ponyville but some ponies fear that this sociopath will bring danger and darkness to an otherwise peaceful existence. Will the mane 6 help Walter Kovac find peace within himself or will he bring them all down with him in his cold views of reality and existence?

As Seen on Equestria Daily!
And our TvTropes page (By Crowrob0t): http://tvtropes.org/pmwiki/pmwiki.php/Fanfic/RorschachInEquestria

My Little Pony: Friendship is Magic and its likeness is owned by Hasbro Studios. Rorschach and Watchmen are owned by DC comics. All rights go to their normal original, intended owners.

War comes to Equestria: with despair, with starvation, with suffering and with sacrifice. And the ponies must learn how to keep true to their values while surviving not just the rigors of battle, but the desolation of total war.