Dean's gut reaction was to yell at Cas--or any angel that might be listening--for YET AGAIN fucking with his family. Was it never enough? Ellen'd come here to help, then vanished. So what did they do?
They took Mary.
That made him want to slap Heaven around. Repeatedly.
It was the way she held the necklace. It wasn't just that it was Ellen's, and that Ellen meant something to her. No. It was obvious that she knew what the things on the shot bead chain meant. That someone had told her. Probably over and over, and over and over.
When she put the necklace back out of sight, Dean managed to look her in the eye. Just like with Ellen, snow that he saw it, really saw it, he could not unsee it. She looked enough like Ellen, and enough like Jo, and somehow she even managed to look just a little like Dean, and Sam.
His heart hurt.
Dean sighed.
"My dad," he began, "always used to tell me and Sam that family was the most important thing. Protect Sam, above everything else. It was just how it was." His lip twitched. "I don't think I'm so stupid that I ended up raising either of you that way, but if you get yourself killed trying to find your sister..."
He made sure he was looking at her, really looking at her, while he said it. Many parents had, he was sure. It was classic, the speech asking your child not to make your mistakes. Dean just shook his head, sure he didn't have to actually finish the sentence.