In Final Fantasy VI, pretty much all of the characters aside from maybe Terra and Umaro could have been the hero of their own SNES era game, part of me thinks that when making the game, they took every canceled project and put the main character into it. The people of FFVII were sort of the same, but their backgrounds were much more intertwined. The characters of FFVIII were purely ensemble characters, without the group, they had no identities, it was like Square's version of "Friends."

In FFX, every single person is a support character. Tidus cheers up the team, Auron is an enigmatic mentor figure, Wakka is a long range attacker, not a protagonist class at all, Lulu's a glass cannon, Yuna's a healer/someone who summons things and steps out of the way, Rikku's comic relief, and Kimahri has like 3 lines.

Okay, not introverted, dependent on the group for their identity. That's a better way to put it.