Katara is an odd character in that she is central to the Thieves & Kings storyline, but after her first appearance as an eleven year-old kid in the pages of the first volume, she didn't step back into the story again until four publishing years later in volumes Four and Five.

Here tale runs like this. . .

Royalty by birth, Katara ran away when she was a child from the city to live in the mighty Sleeping Wood. There she met the trolls, lived under a bridge, and learned from the forest and so grew up to become an enigmatic and formidable sorceress of vast insight and power. --Of all the characters in Thieves & Kings, Katara remains the only one able to confound and challenge the wizard Quinton, her teacher and mentor in a past life. Katara is one of the most powerful beings in all of Thieves & Kings, and I have deliberately tried to stay away from examining her mind as closely as I have the other characters. She retains nearly full memory of all her several hundred past incarnations, and I have decided that rather than try to describe all of her history through the story, to instead leave her on the fringes the described world. She seems more overwhelming to me that way, and is thus able to carry the kind of charisma people have all but forgotten in our world. --The sort, when people come across, immediately want to change the course of their lives in order to follow the person bearing it, which is perhaps one of the reasons Katara left the city. She'd make the pop stars of our world quake in their fashionable shoes. Though nobody has said it, and though she does not think of herself as such, I refer to Katara as, "The Queen of the Trolls."

Rubel is the only one who isn't a little spooked-out by her, but then he has his own qualities with which the world must grapple. Katara and Rubel were destined to fall in love, but whether that will ever happen or not is a question I won't answer here. . .