I agree with all that has been said about Ryan and Eric's relationship. Ryan was very upset when Eric was shot, and referred to Eric as 'my friend' I firmly believe that Ryan, despite how Eric sometimes treats him, does consider Eric his friend and would go out of his way to help him. That is just the way he is. He will get frustrated about the way the team can treat him, but he hides his frustration (except with Cooper- love that scene!) and his primary concern is his job, so he just gets on with it and puts these differences aside.
I think to be fair on Eric he does like Ryan a lot, and he would also go out of his way to help him, but I dont think he is as friendly with Ryan as Ryan is with him.
But I do quite like the tension between these two (except in WISC, poor Ryan!) Anybody working together so many hours in the day are going to clash. Especially when they are 2 strong personalities.