What does the information contained below mean? So Gimle time-travelled back to the present using MU's body?
Avatar is possessed by Gimle after he/she and Chrom defeat Fauder and kills Chrom. When Lucina attempts to escape to the past, Gimle follows her to the past in the future Avatar's body, causing his/her memories to collide with the present Avatar's memories, giving Avatar amnesia.
But that specific body is much older, like at least 15+ years older than the current MU in the current timeline (remember MU in the future was already married and his/her child/children already grew up quite a bit).
So is it more logical to interpret the information as suggesting Gimle time-travelled back into the body of the current MU in the current timeline? This will explain why MU lost his memories due to a memory clash and the fact that the MU has a young adult age and not a middle-aged man/woman.
In other words, the Gimle possessed MU from future time travelled to the current timeline. The Gimle possessed MU then spiritually inserted himself into the current MU's body. This did not change the current MU's appearance in terms of his/her age, but it did cause current MU to lose his/her memories.
Is this a correct/logical assumption?
Note that the war in the future unaltered timeline lasted MUCH LONGER than the 1-2 years you'll be playing in FE13. Arguably, it lasted more than 15 years. Given MU has married and that his/her child/children has actually grown up quite a bit. This is logical because remember Gimle was able to play a much bigger role in the future timeline (thus prolonging the war) and the the future children coming into the current timeline will logically provide some tips/advice/strategies/tactics/crucial information to aid the war in the current timeline.
And of course gotta remember that the very fact that future characters ENTERED the current timeline will have already altered the current timeline's future in ways that no future can possibly predict. The very fact that people or events that are not supposed to happen in the current timeline has occurred means that the future is very much OPEN - thus giving the players a solid and logical way to shape a future in whatever way the player seems fit.