deluded inferiors, straining against my will.
Aurora is one of Widdershin's followers. Once a Descender herself, her World was dying/dead when Widdershin came, so she allowed Gilgulim to consume her World Tree. In Gavada, she convinces the people to use magic to do their work for them, so that Terresia's Mana would be used up faster. She wants to see the eternal world, free from the confines of death, Widdershin intends to create, but is killed be the hero.
Ganser also agreed to follow Widdershin, as he wanted eternal life. He made strict rules forcing the people to never leave Ailily, anyone who went against him he had arrested, to actually be sacrificed to Gilgulim. He is killed by Widdershin, but appears, as a part of Gilgulim within Gilgulim before the final battle with Widdershin.
When you meet Kanonno she is a girl suffering from amnesia and a member of Ad Libitum. Later we find out that she was a Descender. The people of her world were using up so much Mana and killing the World Tree that, in anger and desperation, she killed all the humans there. Alone and afraid, she allowed Gilgulim to devour her World and followed Widdershin. As she tried to harvest Mana from Terresia, the World Tree was so strong it repelled her and she lost her memory. When she sees the Yunanate blossom that your find in the Lavacleft, she begins working for Widdershin again. Upon defeating her, she rejoins you and opens a doorway into Gilgulim for you. In the end, she is able to return with her World Tree Seed to rebuild her World.
Mormo was the Descender of Yaoon, but was unable to defend Yaoon from Gilgulim. Mormo is sexless, but we'll call him a he since he is given a male voice. He's the first to find you under the base of Terresia's World Tree and explains to you what you are and your purpose. He cannot help you in battle. After Gilgulim is defeated he is able to return with his World Tree seed to rebuild his world.
You! the player. I'm not including a picture, because as you know, you choose what your character looks like. I don't happen to have a screenshot of my characters face *sigh*. You are Terresia's Descender. You defeat Widdershin and Gilgulim. With your World Tree safe, you fade away, assuming you return to the World Tree itself, as you are no longer needed.