This is how Optimus and Twilight vs. The Fallen and Megatron goes in
[Twilight stands above the defeated Megatron]
The Fallen: Yes. Kill him. He was weak, broken. Kill him and you can take your rightful place at my side as my apprentice.
[Twilight readies her magic]
Optimus Prime: Twilight.
[Twilight looks at Optimus, magic still ready]
Twilight Sparkle: What?
Optimus Prime: Don't do it.
Twilight Sparkle: Fine.