Dean and Millie took Sam to six flags for his birthday this year. They had never been, and Sam hadn't been back since, well, since he ran away. Those were not pleasant memories for Dean and Millie, but for Sam, that was the best days of his life at the time. He only wished Dean and Millie had been there. They didn't do much, just hung out, had some pizza, Sam felt free. He felt like his childhood wish of that two weeks came true, and he was content.
He noticed Dean and Millie were a little off; they laughed and enjoyed themselves, but something was off. Millie would laugh, and it would die sad. Like she was lost in memories. Dean would trail off too. He'd start telling a story, and suddenly, it would be like he was a hundred miles away. Millie would just lay her head on his shoulder, and finish the story.
Sam had never asked what had happened when Dad and Millie got home, Dean had alluded to something, that time almost 20 years ago now, when they were in Heaven, but he'd never really wanted to know. He knew Dad, what he could do, who he was, but they were Dean and Millie, his idols, his guides, his parents. He never saw them as anything other than invulnerable or indestructible. Nothing ever hurt them, as he got older, he realized that there was still stuff they would only confide in each other about. That they wouldn't tell him. There was less new stuff, but stuff from when they were kids was still hidden; even at 43 years old, they were still protecting him.
They stayed at Flagstaff for about a week, but it wasn't until a month later that he finally asked.
"What happened when I ran away to flagstaff?"
"Dude, what are you talking about?" Dean asked, and Millie moved slightly closer to him.
"When I was 11, and I ran off. I know you remember. What happened." Sam asked again.
"Sam. it doesn't matter, it was 30 years ago. We were stupid kids." Millie said, trying to brush him off. Hoping that, for once, he would just drop it. But it's Sam. Of course he doesn't.
"NO-," he takes a big sigh. "No, that's not it. I can tell it's something big, you guys have always been protective of me, I get it, what I don't get is not telling me the truth, even though it's been so long. If it didn't matter, why wouldn't you just tell me."
Dean and Millie look at each other. "Look, Sam."
"Don't 'Look Sam' me right now. Did Dad do something?"
Dean's hand goes to his throat, without thinking. Millie's goes to her side. Memories flooding their faces, and in that instant, Sam knows.
"Shit, guys, I knew something happened, but how bad was it?"
"Look, Sammy, we would do everything we did again in a heartbeat. Dad wasn't perfect, and yeah, we were just kids to, and I couldn't imagine doing what he did to us, but overall, we didn't have it that bad. We were more scared for you than anything." Millie continued, putting her hand on Sam's shoulder, "Most of my injuries were from the hunt. Dean had to repatch it, but nothing that happened is your fault. Would it have happened if you hadn't run off, probably not, but it also wouldn't have happened if Dad wasn't who he was."
"Look, Sammy," Dean starts moving towards the pair, "you were always, are always our priority. You were more than our baby brother, you were our kid. Sure, I was pretty flabbergasted when that was one of your heaven memories, but you didn't know. We chose flagstaff because we knew it was somewhere you had good childhood memories."
"Dean, Mills, I, I am sorry. I should have asked for something else. Anything else, I mean, the thing is, I enjoyed myself, I had my Bones, but also, I wanted to share all of that with the two of you."
here is a link to what happened at that time.