Some personal favorites

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  The Heart of a Dragon Spike enters a relationship with Celestia when Rarity denies his love. by Razorbeam 82,567 words · 1,760 · 57

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  Fallout Equestria: Pink Eyes Fallout Equestria side story - A young filly begins her adventure looking for her mother. by mimezinga 134,575 words · 3,344 · 80
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  The Last Crusade Four childhood friends discover that their friendship goes back a lot farther than they thought. 5s/4 side story. by CyborgSamurai 130,889 words · 1,187 · 33

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  My Little Marriage : Mary is a Mare Stan has been married to his wife, Mary, for nearly fifteen years. They're happy and live a very normal, almost picturesque life. Sometimes... life has a funny way of pulling a one eighty when you least expect it. by MerlosTheMad 216,808 words · 1,690 · 87