The cutiemark is placeholder until I think of a better one..
Here's Maximus; Starfall's older and more magically talented half-brother. He's the son of Sunburst and Trixie, and has followed in his mother's hoofsteps as a Stage Magician, and Showman. He loves the limelight, and feels most comfortable on stage in front of an adoring crowd. He's especially good at disappearing acts, and using his magic to add a bit of flare to his shows.
He goes through assistants almost monthly, due to his insistence that everything has to be perfect and they're ruining his vision when the slightest thing is off. So while he's impossible to work with, damn if he doesn't put on a good show. Maximus has performed in numerous cities, and for numerous royal Princesses/Princes with many successful and sold-out shows. He travels a lot, but frequents the Crystal Empire since it's where he grew up. (He also loves that Crystal Pony shine he gets being there).
When Starfall gains her dark magic powers, Maximus is the first pony she uses it on, cursing him to be invisible to everyone and taking away that limelight he oh so adores. Maximus, terrified of his sister and what she's done, hides away. He doesn't like being around other ponies while like this because it's like he doesn't even exist. He talks, they don't hear. He stands in front of them, and they pass straight through him. He can still pick up objects and interact with stuff like doors, but ponies freak out when a door randomly opens and they don't know what did it. (And while he can pick up a pen and write, all the words come out garbled, Starfall didn't want him to talk to anyone. Hence the curse.)
Once Starfall is defeated, Maximus, who's becoming more and more despondent, finds out that his sister is the only one who can still see and hear him. He now has to figure out a way to convince her to undo this, all while she's under arrest for crimes against the Empire… Maximus has a tough road ahead of him :/