This idea came to me when I was scouring deviant art and found this image:

So here is the premise of the story:
(Takes place before season 6)
After being banished from Equestria along with her hive Chrystalis is out to get revenge. Her plan is to befriend the elements of harmony so that she can get close to the princess and "remove" them from getting in her way. There is one problem, Equestria is on the constant search for changelings. So as her last option Chrystalis turns her self into a pony using a potion. Well she be successful in taking out the princesses, or will she learn what it means to be a pony?

My only restrictions for this are:
Keep it teen or lower.
If your going to ship female characters with Chrysalis than keep me anonymous.
Have fun!