They love to playfight together, above is a video of the two of them playing in the living room. At first we walked Diesel off lead in a secure park as we were not too sure if he would come back easily. Thankfully he seems to realise we are his "pack" now and follows Millie everywhere. So when we call them, they both come back.Yesterday and today we have walked them both off lead in the woods and open park. He has been very good and has come back, albeit not as well as Millie does when he is distracted, but we have not struggled as yet.