So my first theory is kinda so-so. I was thinking that maybe, the original apprentices weren't all transformed in Nobodies/Heartless just around the time Radiant Garden fell. Perhaps those original six stayed behind at the newly dubbed Hollow Bastion and set to work transforming the rest of the castle (since before and after the Garden underwent huge technological changes. Remember the big Heart symbol etched into the castle that was half stone and half gears?) Maybe there was still a little life left there in Hollow Bastion for a while, since how the hell would Saix and Axel have been able to scheme to join the Org. and then take it over, unless they knew of the group and what they had to do to join?
Anyway, that's theory 1. Theory two revolves around Zexion's Illusion element. If someone else has already beaten me to the punch with this one, to hell with it anyway. Maybe Zexion isn't as tall as he is made out to be? Maybe he's using his element of Illusion to continuously cloak himself to appear to be more on the level with his fellow Org. members? I'm sure Larxene and a few of the others (Xigbar too) would probably never let him forget how much of a shrimp he was if he stayed short the entire time. Imagine the jokes of seeing such a little kid (or maybe he's just Short for his age) in a lab coat, or the black and decked out (and mysterious) org. coat. He still seems very young in the Kh manga, but make of that (canon or not) what you will. What helped this theory is thinking of Tsunade from Naruto, who keeps herself looking much younger than she is, all the time.
Please, now feel free to tear apart and examine these theories as you wish.
Anyway, that's theory 1. Theory two revolves around Zexion's Illusion element. If someone else has already beaten me to the punch with this one, to hell with it anyway. Maybe Zexion isn't as tall as he is made out to be? Maybe he's using his element of Illusion to continuously cloak himself to appear to be more on the level with his fellow Org. members? I'm sure Larxene and a few of the others (Xigbar too) would probably never let him forget how much of a shrimp he was if he stayed short the entire time. Imagine the jokes of seeing such a little kid (or maybe he's just Short for his age) in a lab coat, or the black and decked out (and mysterious) org. coat. He still seems very young in the Kh manga, but make of that (canon or not) what you will. What helped this theory is thinking of Tsunade from Naruto, who keeps herself looking much younger than she is, all the time.
Please, now feel free to tear apart and examine these theories as you wish.