Lucky for Dean, he’s quite a bit older for Sam. He’d been living on his own for a few years when Sam caught him, and wouldn’t see Walt or Mallory right after his capture. They’d find out when he wanted to approach them with it… which with Dean, could be at any time. He’d wait long enough to be sure Sam wasn’t a threat to anyone, then go talk to them.
Sam and Walt tend to explode at each other, Dean and Walt have a mutual respect for each other. So the dynamics of the family is a lot different in either universe