So one of the things of note about Karthus is that yes, rumors spreading hundreds of miles east paint him as a man who can speak with the dead, but you never actually see him do it. Karthus to me has always been a terrifying figure because he's a preacher, he's a reverend, he's a singer -- he can convince you through fire & brimstone sermons and beautiful songs that being a mindless, undead thrall is better than drinking the poisons of life. He very much matched the idea of the wild west roadside proselytizer, condemning the sons of perdition for whatever reasons and building a commune out where there could never be a resistance mounted against him by anyone.
Yorick strikes a much more tragic figure, and isn't actively trying to hurt most people. He's a dude trying to make things right in a way that probably won't even help, haunted by a past that literally follows him around whispering in his ear. He's also not a preacher -- he's a monk and a gravetender, and seems sorry he has to be violent at all. He wouldn't have worked for what I was planning for the story.
Hope that answers your question, and I'm glad you liked the read!
