A lot of you seem to be under the impression that the Changelings have not been active since the war, incapable of surviving in the hollow, loveless backdrop of the wasteland. Naturally one can see how you would believe this, it is all together easy to dismiss them as a threat from the past wiped out from starvation or otherwise temporarily removed from the equation. But I am here to tell you the truth as I have seen it with my own two eyes, the truth that they don't want you to know. They never went anywhere, in fact they are stronger now than ever before.
Horse apples you say?
Cant blame you for not believing me, most ponies don't. I know I used to be like you, ignorant of the truth that lay right before my snout. Its a lot to ask someponie who has never traveled far enough north to make it past the borders to believe, most just write me off as A loon shooting my mouth off but I'll never stop trying to convince people of the very real threat those monsters at the Institute pose to the wasteland.
That's right, the institute, the place everyone says is just a old ponies-tale. But it aint no legend, its real. Settled far to the north of Equestria, settled deep in the heart of a crater hidden smack dab in the middle of the desert. I hear tell that it used to be some sort of school, not sure if i believe that but whatever it was must have been important enough to warrant a shield powerful enough to survive at least a few direct assaults from the Mega-Spells. Its a bit worse for the ware, but the place is still up and running, only now its under new management.
Every year they send out a hand full of the monsters, not many, just a few dozen to make the trip south and implant themselves. They take over the lives of traveling doctors, rag-tag hero's, activists, brilliant scientists, whoever they think stands a good chance to really help the wasteland. For months, or in some cases even years, they maintain their disguises and fight tooth and nail to improve whatever community they have latched onto. Towns prosper, hopes rise, love for the hero spreads.
That's when the Swarm comes, not that you would be able to tell who they were from a glance. Usually they appear as some sort of roving gang or raider group, occasionally they have even been known to impersonate the steel rangers. Some places try and fight back, but it never works out. By this point the false hero's have all but complete control over the hearts of the population.
Once the feast is over they retreat back north, wait a while, and repeat the whole damn thing over again. Sometimes It docent work the way they want it to, in fact rarely do they get the opportunity to devour anything larger than a trading post, but they are still a big problem. Over the last ten years no less than three large settlements have disappeared, and I know for a fact at least two of them were targets of the Changelings.
...But I can see from your face that You don't believe me.
Fine, be that way, just sit around all day and enjoy the sudden prosperity. Me? Im leaving town before it becomes number four. You can call the sheriff the best thing to ever happen to this place but I know the truth, I know what he really is. They tried to cut the truth out of my head, but I made it out of their sick little fun-house, and I don't plan on letting them lay hoof on me ever again.
Enjoy being dinner.