By now you know these two are always together. This is Polly on her way to starting a fight with Bates by pouncing on him. Their fights consist of the growling noise, but rarely any actual bites. Polly will bump him with her nose then pull back and growl and bump him somewhere else with her nose. His method of fighting is more like a game of slaps where he reaches out with his paws. He is less of a growler than she is, but when he is done fighting, he will let her know by overpowering her and ending the session.