Edgar is as much of a main character as Locke is. I voted Terra however, since she's the first character you control. Technically though you can beat the game without even getting Terra or Locke in the world of ruin.
Locke
Terra
Other
None
Edgar is as much of a main character as Locke is. I voted Terra however, since she's the first character you control. Technically though you can beat the game without even getting Terra or Locke in the world of ruin.