I am back (and need help)SPOILERS

[Future Esthar]

As I said,Vaan an Reks are amnesic and probably suffered from some kind of trauma.They wouldn´t remember even they age.
If you go to Phon Coast you will find there is a bujerban who falled from the sky and losed memory.
Vaan´s "imaturity" can be explained by the fact that he knows little of the world.That´s why he grows quick on Revenant Wings.
Balthier and Reddas act strangely near Vaan.Reddas even more.He puts too much confidence on him later on.
Balthier goes as far as letting him drive the Sthraal.
And Old Dalan seems to know a lot.
Vaan´s desire to be a sky pirate could come from a possible judge past(because he is a Solidor).
And Reks seems to have good fighting abilities for an amateur.
His feelings concerning his and Vaan´s opposition to the government probably spoiled and he joined the Resistance.
Vaan also acts strange toward Vayne sometimes and near the end of the game he seems to be physically stronger than Vayne.
A fat building don´t necessarily imply an older brother.
I would go as far as saying that Vaan is older than Reks.
And we know what that means,don´t we?