It somehow did not surprise Starlight to find herself sitting in a chair when she came into her room. There were a number of different reasons this could have happened, but there was one she had always expected would. Disrupting the time stream, nearly shattering the universe, attempting to ruin harmony and destroy Equestria… there would be consequences. It was inevitable.
Twilight had taken mercy on Starlight. She wasn't so sure she would do the same for herself.
So finding an alternate version of herself waiting for her was something Starlight had prepared for. After a momentary startle (which was entirely understandable given the circumstances) she took a deep breath and bowed her head. "I surrender."
"I'm not here to arrest you, dummy, I am you." Starlight paused before clarifying. "I'm not an alternate dimension version here to throw you into prison, I'm you from a week in the future."
Relief flooded through Starlight and she couldn't help but smile.
Then she realized just how much had to have gone wrong for her future self to open up the time travel can of worms again. Grimly setting herself to task, Starlight nodded. "Alright. What happened."
"Pinkie Pie."
The earlier Starlight shuddered. Pinkie Pie had caused something severe enough to need Starlight to change the timeline. This was bad.
"She unlocked time travel."
"Oh no."
Future-Starlight nodded, mouth drawn to a severe line as she rose from the chair and closed the distance between them. "She promptly shared it around all of the girls, who used it for what they decided were important purposes."
"Oh no."
Starlight let out a long sigh. "Then Fluttershy let Discord have it, who gave it to Trixie."
Present-Starlight slumped to the floor. "Oh Celestia. We're all going to die."
"So currently - in my timeline - the dinosaurs are back, Rainbow Dash and Applejack started dating shortly after they were born, there are almost a dozen Rarities running their own production line and possibly sweat shop, and Trixie was arrested for winning every lottery in Equestria simultaneously." Future-Starlight shoved the scroll into her past self's hooves. "Fix it."
Shaking, Starlight looked at her own hornwriting on the spell that had created so much chaos. "I'm not sure we can fix this without creating too many paradoxes. It could rupture the timeline."
"There's already dozens." Starlight's voice quivered with frustration. "You're starting far back enough that you'll be replacing all of them with just one paradox: me giving you the scroll. It's the best we can do." She paused. "And once you're done, I suggest throwing the scroll through the mirror portal. It worked for Starswirl, after all. Let Sunset and her mostly magic-less world deal with it."
Unsteadily, Present-Starlight rose up. Her eyes were fixed on the scroll, still trying to take in everything that had happened. "Right…. right, yes. Gotta fix the world. This is my spell so it's my responsibility. You can do this, Starlight. You have to do this." She unfurled the scroll and began to cast. "And then I have to make sure this never happens again."
As she was sucked into the portal between time, her future self shouted at her. "OR IN THE FIRST PLACE."