Takes place right after Every Little Thing She Does. For the purposes of this story, Mirror Magic takes place early Season Six.
While trying to deal with the guilt she feels after mind-controlling her friends, Starlight Glimmer accepts an invitation from Sunset Shimmer to spend the weekend with her in the human world. But while she's there, a magic device she created to warn her if her human counterpart is nearby goes off. Instead of leaving or staying away as she had initially planned though, she finds the idea of what her life could have been like in this different world, a life without the magic that constantly leads her down the wrong path too compelling to resist. Ignoring Twilight's warnings about maintaining the balance between the two worlds, she tracks down her human version instead.
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So, I’ve gone ahead and marked this complete. I know that probably isn’t very satisfying, and I know people were waiting for the last chapter, but writing isn’t really something I can maintain in anything other than short creative bursts. If I can work up the creative burst to add a final bonus chapter, well, than this will get another update. If not, than it won’t.