Thanks, Tunnels. I thought for a moment that the "gate" terminology was just an artifact of translation.
But can that be possible? Time is malleable because a person is at a 4D point with the capacity to change the future, but if a person's at a 5D point, they're outside the flow of time, and can view the evolution of history.
I would argue that they are not so much changing the future as changing the present, from which the future is determined.
A form of the future has to be set for time travel to be possible. When Crono travels to 2300, he sees
a future, therefore a future must exist for him to see. Perhaps this is just the result of the likeliest of outcomes being the outcomes assumed by time. Things don't have to go that way, but unless the shadows of these events remain unchanged...
From the standpoint of 2300, any freewill decision in 1999 AD has already been made, but from the 1000 perspective, any freewill decision in 1999 has yet to be made. From a regular, 4D, time scale, both are true. But when one adds Time Error, 1000, 1999, and 2300 are all "in the past" (the events of each have already happened, and so freewill, if it exists, has already been factored into the equation that produced those time periods). From a TE perspective, regular time is static: change can't happen on that level. Thus, Time Error and time travel in general is what allows for a new variable to be entered into the equation of time. Freewill on a regular time scale exists but is already resolved. Freewill on a Time Error scale, however, is happening in the present.
Lavos Invictus existed in Time Error past; the Lavos that exists in Time Error present lives in a regular time world in which the future is just as set for "him" as it was when Crono first traveled to 2300 AD.