Brian letting Justin be himself is one of the most beautiful things about the love for me. One of the best examples I can think of is after Vic dies, Justin does what's best for him and goes back to the house. I also love how in season 3 both the girls and Deb let Justin know he was a part of their lives regardless of Brian. And how he KNOWS that so well that in season five, he visits the girls after he gets back from LA.