Equestria Computer Aided Science Enrichment Center · 7:18pm Dec 7th, 2017
The basic idea is that somebody gets displaced then turns into GLaDOS.
However, he or she (preferably she) aren't GLaDOS when they first arrive. Whether their still human or a pony is up to the wrighter.
Finding themselves in Equestria, the main character tries to make the best of their stange and new situation, even going to a collage in Equestria. This eventually leads them to apply a job at the Equestria Equivalent of Aperture, where then, thru a series of rather unfortunate events, the main character gets turned into GLaDOS.
What happens after that is up to the wrighter.