Starfall is the kid of Starlight and Sunburst, she's gotten a redesign since the last time I drew her, still not sure about the cutiemark, but it'll do for now.
Starfall has a half-brother; Maximus, who is the son of Trixie and Sunburst. Their parents all live in a herd together so they grew up together as siblings. Starfall resents her brother because she should be the one with the more powerful magic. Her mother can do all these feats, even accomplished time travel! While Max's mother is just a stage magician, how is it that magic comes so easily to him?! And then to add insult to injury, he doesn't even use it! He prefers to follows in his mother's hoofsteps as a stage magician! Furious with the injustice of it all, Starfall spends her time trying to research any and all ways that she can get better at magic. It's during this time when she's pushing everyone away and secluding herself, that a certain shadowy colt finds her and starts promising her power… Tenebris (fav.me/ddqh3qn) needs her help to sneak into the Empire. The Crystal Heart, while not a threat when not in use, can harm him as it did Sombra if it was used. Tenebris is also not the most inconspicuous pony out there, what with his bright red horn on his head. So he convinces Starfall to work with him. She gets to use all his dark magical powers, and he gets to hop a ride as her shadow into the Empire, unseen.
(This all goes a bit downhill though because he didn't anticipate just how crazy with power Starfall would become when gifted powerful magic. Everone was in a quite a shock when after defeated, Tenebris; Crystallo; the LOST PRINCE, suddenly appeared. Tenebris gets to find out all the secrets the Umbrum were keeping from him…)
Starfall lives in the Crystal Empire with her father, and always tries to look her best, constantly concerned with her outward image and how ponies perceive her. She has low self-esteem, and anxiety due to her lackluster magical abilities.
(Not sure what her talent is, so her cutiemark might change in the future once I figure that out)