Gabriel Guado is an original character created for Legendary Guardian and has no basis in cannon from Square Soft in Final Fantasy X. He is one of Auron's temple roommates during his early years as an acolyte in Bevelle.

Gabriel, in LG, is noteable for several reasons. He is a pure Guado child and the first to ever be admitted to temple training as an acolyte. Gabriel wants desprately to be a Summoner, though the reason for this wish is never explored. Auron quite admires him for his dedication and focus.

Sadly, Gabriel's life is ill fated. At the tender age of nine, he and two others decide to enter the Trials. The rest of that story spoils too much plot to give away here. You'll have to read LG to find out what happens.