So, writing relationships is hard.
No. Writing relationships is easy.
Writing real, functional relationships is impossible because no sane person can account for the thoughts and desires of two different people. We try to, and everything we try is only a cheap imitation. We come close, or close enough. Some people can write very believable relationships between two fictional characters, but not a single one is perfect because a fictional character can't be thought out fully enough to make them real.
When writing a relationship, you do so to establish what each character is and does. You can learn a lot about a person by seeing what they do, but you learn a lot more by seeing how they act around and toward people AND how they act toward their self.
John took his sword in-hand and cut down seventy-three of his foes.
John saw his friends from a distance, but avoided them by taking a side path. It wasn't that he didn't want to see them. He simply didn't want them to see him.
John looked at himself in the mirror. It was a perfect reflection, and he hated it. He wanted to smash the mirror, but instead set it calmly on the dresser.
In each instance, we see John act and interact (or fail to interact) with objects (the sword, his enemies), people (his friends), and himself (the mirror) and each gives us a different kind of information regarding who he is. His interaction with obstacles shows us his physical capabilities. His interaction with the people and objects around him shows us his personality. And his actions toward himself show us how he feels internally without necessarily being able to read his every thought.
Believability comes from consistency in developing a character, making sure they do the same things in certain situations, and giving depth to them, revealing their character in layers via increasingly complex situations of the same type. Making Eryn Thompson, the Arbiter, into a believable character will be a combination of being able to see his actions and read his mind, but the characters around him are the challenge. Making them believable will rely on interactions with each other and with Eryn, using him, really, as a blank canvas upon which to paint the people around him.
Because we will be seeing everything from Eryn's viewpoint, it will be other characters we're getting to know. Eryn already knows who he is, and he will remind us fairly constantly, but we'll be learning about the people on his journey through Terra the same way he did, by seeing how they work and interact around him.
The hope is that you'll learn about people in the book the same way you learn about them in real life, and I think that will add realism and interest.
Here's hoping.
And here's to the future. :)