Alternatively to what Zinrahzul said, you could use kul instead of rii.

Kul means "good" as in morally good, which might be closer to the connotations of the word "pure" than "essence" would have.

You could replace rii with kul in his name suggestions, and see if you like the sound of those better. Both options are entirely valid, of course. It's up to personal preference by that point. My advice is to look at the definitions and connotations of both words and see which one better fits the personality of this Kathryn Everett.