Now, before my story goes any further, there is one last facet of my power you must know about. And it’s the most critical part of my power.
Using me as an example, and pretending that someone else might have the same power as me, I’ll describe this as best I can:

When you have this Time Travelling ability, you set yourself in a certain Timeline—your Present. But when you travel (intentionally or not) into The Past, you’ve entered a new Timeline that runs in tandem with your Present Timeline.
With me so far?
But you must remember The Past does eventually lead into your Present. Which causes a certain problem.
If you change one thing, just one thing in your Past, and that Thing is a drastic piece of your Present, then BOOM!
Your Present Timeline vanishes.
Disappears.
Fucks off.
And it can’t come back.
Which means you’re stuck on your Past Timeline, as it has become your Present.
And that also means you must stay there if you want to get back to (what once was) your Present…