This is how Twilight vs. Von Nebula goes in
[Twilight wakes up and sees Von Nebula standing above her]
Twilight Sparkle: Where is she?!?
[Von Nebula steps aside, revealing Princess Celestia behind him. Twilight is shocked to see her]
Twilight Sparkle: Celestia...
[Von Nebula lifts his arm, as Celestia rises in the air, slowly being choked]
Von Nebula: Bow before me, or she dies.
Princess Celestia: [choking] Twilight...
[Twilight pauses, before she sees Celestia get choked more and more]
Twilight Sparkle: Wait! Wait!
[Twilight remorsefully bows before Von Nebula]
Twilight Sparkle: I will do your bidding. Just let Celestia go.
[Von Nebula releases Princess Celestia, who falls to the ground]
Von Nebula: Find and kill Stormer. If you refuse, your former teacher dies.
[Celestia stares on]
Von Nebula: You will return to me and give yourself to the dark side. If you resist, she dies. And when your training is complete, you will hunt down and execute the former comrade of mine. If you fail, she dies.
[Twilight stands and her eyes open, revealing they are now nebula blue]