Though the original Elements of Harmony artifacts were lost many years ago, an older Princess Twilight Sparkle proposed an idea to her friend and former student, Sunset Shimmer: if the Element analogue Geodes from her world were to be brought over to Equestria, perhaps the magic of the Elements could be reignited. Sunset, who had been considering a permanent move back to Equestria by this point anyway to raise her family, complied–and the Elements of Harmony (though now with an added seventh Element, Empathy) would soon be reborn into the world through seven foals, rather than re-manifesting as magical artifacts. This time, not only were the Element bearers embodiments of their Elements, but the physical forms of them as well.
 
Mirage, the child of Trixie Lulamoon and Starlight Glimmer, grew up vaguely aware of the lost Elements and Princess Twilight Sparkle’s search for their new forms, but did not realize they themself were one of these seven Elements until late into their teenage years. They represent and embody the Element of Magic, much to the conflicted feelings of their two mothers.
 
(They are nonbinary and use any pronouns.)