This is how Twilight saves her friends and Twilight betrays her friends goes in Sideswipe's Sirenix.
[Fixit activates the Spacebridge]
[Megatron prepares to fire when Twilight jumps in the way]
Twilight Sparkle: Decepticons, leave this place or die! [fires a beam of magic]
Megatron: Princess Twilight Sparkle. [gets hit by the beam]
[The Vehicons run as Starscream and Soundwave help their leader up]
Starscream: Cowards! [fires his missiles] Fight on!
Princess Celestia: What did you see, Twilight?
Twilight Sparkle: [straining] Darkness... cold. Then, light.
Princess Luna: What?
Princess Celestia: Darkness, light?
Twilight Sparkle: Must... complete.... plan. [walks off]
Princess Celestia: Yeah, what is the plan?
[Later, the ponies stand near an airlock]
[Twilight is building an escape ship]
Applejack: Twilight built herself an escape ship.
[Twilight lowers some pieces]
[Celestia looks at Twilight]
Princess Celestia: Twilight.
[Celestia goes over to Twilight]
Princess Luna: Tia, no!
[Celestia ignores her and continues. Twilight turns]
Princess Celestia: Twilight, this is yours.
[Celestia levitates the Element of Magic. Twilight backs off]
Twilight Sparkle: [reacts as in fear] No... no!
[Celestia moves it to her and Twilight, fighting herself, puts it on her head. Celestia smiles]
Princess Celestia: Twilight, is something wrong?
Twilight Sparkle: Forgive... me.
Princess Celestia: For what?
[Twilight blasts Celestia with magic. Twilight then grasps her head in pain]
[Twilight then blasts the others and gasps]
Twilight Sparkle: What... have... I... done? [strains] Must... complete... mission!
[Twilight activates the controls]
Computer: Auto-destruct activated.
[Twilight looks around and teleports away]
Princess Celestia: Twilight! What has gotten into you?
[The alarm goes off]
Computer: Beginning countdown to self-destruct.
[Celestia gasps and teleports herself, her sister, the Autobots, and Twilight's friends away]
Computer: Self-destruct will commence in ten, nine, eight, seven, six, five, four, three, two, one.
[The ship explodes]
[On Earth, Sideswipe stares at his photo of Twilight]
Sideswipe: [sighs] Twilight, I miss you.
[Celestia, the Autobots, Luna, and Twilight's friends appear]
Twilight Sparkle: Optimus, Bulkhead, Ratchet, Bumblebee, Smokescreen, Arcee, they gave their lives, so that I might return to Canterlot.
Twilight Sparkle: Umarak left no survivors.
Grimlock: Umarak? I want to stomp Umarak flat into the ground!
Twilight Sparkle: We will mobilize all our forces, and move against Umarak. That tryant is gonna pay for this but this time for good! I mean it, like there's no tomorrow.
[With Sideswipe and the others]
Sideswipe: Twilight. There's a dark energy within her. One created by Umarak.
[Suddenly, Sideswipe feels pain, grasps his head, and collapses to his knees]
Princess Celestia: Where is everyone?
Grimlock: All go smash Umarak.
Princess Luna: Umarak? What has he done?
Strongarm: He killed you. Twilight said so. Something's not right.
[Sideswipe is still in pain]
[Rainbow Dash places a hoof on his head]
[Rainbow then sees Twilight on the screen with the other Autobots]
Rainbow Dash: She's taken the whole fleet.
Arcee: Not the whole fleet.
[Ratchet approaches Sideswipe]
[He scans him]
Ratchet: He's in unpredictable pain. And I think it has something to do with Twilight's dark energy.
Fluttershy: Hang in there, Sideswipe. You're gonna be alright.
[Sideswipe strains and puts a servo on his head]
[Fluttershy looks at him]
[An alarm goes off]
Applejack: What's that?
Bulkhead: Twilight's dark energy is acting up again.
[Black electricity crackles across Sideswipe's head]