My favorite character as of now would have to be Nameless, an alternate form of Rin Dragonborn. Nameless is this funny yet serious character that I love to put in different situations to see how he reacts.
Crystal has to deal with the most pain during my story. She had to deal with losing two limbs, her eyesight, and one of her eyes within the first few books. Not only that, but she had to deal with the murder of someone she cared about that she could have prevented easily and the lack of trust that everyone gives her because of a few misunderstandings.
I struggle most with writing Leo because I cannot connect his personality with mine or anyone that I know. I avoid writing with him a lot because I don’t know how he would react in most situations, but he is very important to the plot and I can’t just leave him out of the story.