Furi's typable characters:
The Rider - ISTP 8w9
The Voice - xNFJ 2w1/1w2
The Chain - Sadistic ESTJ 8w7
The Line - INFJ 9w1
The Hand - ISxJ 6
The Song - ENFJ 2w1
The Burst - INTJ 3w4
The Edge - ISTJ
The Burst - ISFP 6w7
The Rider is an unstoppable character with a purpose. He's silent but deadly and strong, taking down everything that puts in his way, he doesn't hurt anyone that don't have the intention to do, he's an 8w9. The reasons for ISTP is that he applies logic and a quick way to solve problems, he's not emotional or idealist despite that in the "good" ending he shows devotion and empathy for the earth people. Even if he doesn't intentionally shows any emotion, you can, somehow, note how much does he become emotionally exhausted during his travel which is another inferior Fe trait.
The Voice is a nurturing father who had once a purpose to protect the earth habitants, however, he got trapped in his own prison, where he became completely unhealty(enough to free Rider) and he got a plan to get out of it.
Same for Rider, you can see how exhausted he becomes the longer the travel is, as he sees what is he doing. As an NFJ, he can't hold his own emotional attacks that are made by his resentment to you and, at the same time he overbursts in emotions, he wants to make you think that you're not alone and make you turn "good".
The Edge, not as Rider, is a more constant and intense person who can train an eternity to fill his purpose.
Another proof is when he leaves the sword and picks HIS oar, which is a technically less effective weapon, but as is it HIS weapon he feels much better with it, it is the item of his life.