There was surprisingly little outward agression within the packs, but like any happy family, each member knows their place. Mostly they seemed to communicate with their bodies; their posture, their eyes, the subtle showing of teeth.
Sort of like any of us before coffee in the morning.
I've read that this *kissing* among wolves is a left-over submissive behavior, a relic of their puppy days begging to be fed. A behavior that we witness in our couch-potato dogs, still. These two were siblings, if I remember correctly, and both seemed to relish the mouth to mouth contact.