Chrono Fantasy XIV

[Yucie]

As for the power of the echo, we really don't know much about it. We could be reading and manipulating memories as far as we know.

That's exactly what the Echo is.

The Echo allows the user to dive into the usee's memories, and experience them firsthand as though they were happening right before the user's eyes; and, to an extent, you can interact with that person's memories and manipulate them, and they WILL have an effect on that person. But the changes of a memory only effect that single person and nobody else.

The Echo isn't so much time travel as it is diving into a person's subconscious to view their memories in real-time.