Headcanon submitted by Anonymous
Guest illustration by Cybersp0nge (who assures us with all the honesty a perv like him can muster that he was not the anonymous submitter). His Tumblr blog is here. It’s easy to tell that he’s given pony-shipping plenty of thought before, which is good to know, since he’s making an animated parody of the show and all.
All the ships are listed in the tags, so if you don’t understand any of them, check the tags on the original post.