"What is the greatest accomplishment of your life?"
That one stumped them.
"I'm barely eighteen," Cas offered. "What great life accomplishment could I possibly have?"
"Living to eighteen," Dean suggested. "That's mine."
"Really?"
"Yep."
"Oh come on, you gotta have something better than that."
"...Don't think so."
"Dig deep, Dean, come on. For example, my greatest life accomplishment was building a tree house with my siblings. Built it all by ourselves, and took all summer, but it was worth it."
"Alright alright," Dean searched his mind. One thing stuck out at him, but he didn't want to risk Cas piecing two and two together. But he also didn't have any other life accomplishments. "Keeping my little brother safe. That's my greatest life accomplishment."
"What do you mean?" Dean shifted uncomfortably in his chair. He hated even nearing the topic, but Cas seemed easier to talk to than most people.
"Sam's never gotten hurt. Not while I was there, and trust me, there were plenty of opportunities where he could have. But I protected him, I kept him safe, and that makes me proud of myself. It's one of the very few things I'm proud of myself for, actually." Cas studied him.
"...You had to protect Sam from your father, didn't you?" Damn. He should've known Cas was too smart to not figure it out.
"Cas-"
"Does he hurt you?" Dean stared at the table. He didn't say anything, but that was answer enough for Cas. "Dean-"
"Don't worry about it."
"If he;s hurting you, then you have to tell someone-"
"Someone already knows. Plenty of people know. Hell, now you know. Big difference that makes."
"You should go to the police," Dean barked a harsh laugh.
"And what? Get beaten to death while we wait for them to show up? Have a gun pointed at my mother's head while I try to convince the officers at my door that nothing's wrong, that it was a prank call because I'm a stupid kid who over-exaggerates? Risk my father breaking down the bathroom door and hitting Sam while I'm on the phone calling 911? No thanks."
Cas didn't have a response to that one.
But at least now he knew the real reason Dean was grateful for locks on bathroom doors.
They kept his father away from his brother.
And Winter was cold, so he could wear long sleeves to hide any marks his father left.
"Let's just move on with the stupid questions," Dean grumbled, reaching for the cards.