I've defeated three of the four Lords of Cinder, which is when I expected Leonhard to
based on what I've read on the Fextralife wiki. However, he still hangs out at Firelink shrine encouraging me to invade all I like. Are there other prerequisites to cause him to leave Firelink Shrine? I have a theory on what it might be, but I don't want to try it in case it beefs up someone else's quest.
My idea is to offer Rosaria one Pale Tongue, but I don't want to make Sirris mad at me for that, since I still want to summon her for some fights.