Technically, this is Sunset Shimmer with Sci-Twi, but because counterparts Sunset and the other Twilight would still make Eventide. Just subtract glasses and add wings, and adjust outfit accordingly.
As for personality, Eventide is just as smart and magical as you’d expect of the fusion of two magical prodigies. She can be overconfident, and definitely lacks some common sense, like safety precautions on her experiments(Has been known to set themselves on fire more than once). She is fiercely protective and is prone to figurative(and literal) explosions when an experiment goes wrong.
*I did use the Future!verse designs so extra hair streaks.