Although you have a set four characters from the beginning of the game, you still have several companions that help you through your journey. Each with a different background and story.
Princess Sara - The pretty (although sometimes childish) princess of Sasun Kingdom. Accompanies you in the Cave of the Seal to defeat Jinn.
Desh - Went to the mountain looking for something. Accompanies you in your quest, after you run from Bahamut.
Cid - Master Airship creator. Helps you build two ships. Lives in Canaan but was stuck in Kazus when Jinn's curse was laid.
Elia - The kind Maiden of Water. Accompanies you to the Water Crystal after you cure her. She is the only one who can open the sealed door in the Cave of Water to reach the Crystal.
Prince Allus - Accompanies you to find out why his father the King of Salonia is acting so mysteriously.
Unne - The guardian of the World of Dreams. When you first come across Une, the parrot will explain the situation. Accompanies you to find the great Invincible (an airship).
Dorga - A great wizard. Accompanies you through the Magic Circle Cave and modifies the Nautilus to travel to the depths of the sea.