John was frustrated. Dean used to be the easy one. Part of him wished he could go back in time and redo everything. Maybe then his sons wouldn't be in this mess, and his family wouldn't be falling apart at the seems. It killed John to see his sons like this. Sam was beating himself up about the future, and Dean was trying to prevent it to save Sam, and the cycle continued. Blame, anger, hurt, blame, anger, hurt. He didn't know how to fix it, or if he could do anything. Maybe he'd already had his chance and since he blew it, that was it.
He didn't know how to get through to Dean. What was he even hoping to accomplish by getting into the panic room with him? They'd spent the last few months at wits end and doing nothing to fix it. Drinking and arguing didn't help calm the tension, if anything it made it worse. But John was out of options. The only thing that came to mind was literally beating the sense into him, but didn't that make him an even worse father? What parent felt like taking their rage out on their kid?
Him. That was just how he'd been raised. His eyes watched dean carefully as he answered with his smart assed flippancy and John simply lost it. He crossed the distance between the two of them and grabbed at the collar of Dean's shirt, pulling him in close much like he'd done with Sam those few years ago when they reunited at his college. "Did you even stop to think what it would do to this family, to your mother?" To me? He desperately wanted to add, but couldn't find it in him to do so.