When Trixie casts a spell on her and her young filly with a ancient artifact, Twilight and Nyx awakens in Cantorlot. Seems pretty normal, right? Nope, because she and her young daughter has become foals and cannot even recognize herself, or should I say, her selves.

Nyx is from Past Sins by Penstroke. If you don't know it, you probably should read it.