I think there's another. I've felt the pull, but I don't know who or what it is.

[he hasn't been near Tir enough to realize]

That...is something you'll have to figure out for yourself, unfortunately. It takes time just to be able to develop the right relationship with the Rune, to separate its voice from yours. Eventually, you'll be able to tell when it's trying to push, and that you should push back.