Watching humans was interesting, Jack decided. He had spent the entire day outside with Castiel, and his father had given him a lot of interesting thoughts on humanity from his angelic viewpoint. One that wasn't filled with the contempt that Lucifer had tried to feed him. No, Castiel's view was a colorful mix between confusion and awe.

When they returned to the bunker Sam and Dean were in the library with two cups of coffee steaming between them. Castiel snuck into the kitchen to get his own cup while Jack sat down beside Sam.

"Hey. You had a good day?" Dean asked conversationally.

"Yes, I learned a lot," Jack said.

"Yeah, like what?" Sam wondered.

"Like, did you know that language alters how humans think?" Jack looked back and forth between Sam and Dean who shook their heads silently. "For example, there's an African language that use directions a lot. Like, when they greet someone they don't say hello, they say, "In which direction are you going?" and they have to know all that. They don't even use left or right, so if someone hurt their leg, they describe it as a pain in their south west leg. So, because their language is like that, those people think a lot about orientation and enviroment."

"Wow, that's interesting," Sam said. He was clearly amused at Jack's excitement as he was speaking. Since the defeat of Lucifer and Michael and Dean's return, things had slowly calmed down. The people from the other world had slowly started to intergrate into their new home here where they were stuck and Sam and Dean had decided to take it easy for a while and lick their wounds, mentally and physically, while they could, while Mary had decided to help some other hunters. That meant that Jack and Castiel had more time for bonding than they'd ever had before, so they had made it a habit to do things, only the two of them.

He usually told Sam and Dean all about it, but tonight he had a much more pressing question. He waited until Castiel joined them with his own steaming cup of coffee before he asked it.

"So, um. I was just wondering something."

"What is it?" Sam encouraged.

"Well, we saw a lot of families today. I just thought that everyone in those families has a role, like mom, dad, brother, aunt. What exactly are our roles?"

Sam, Dean and Castiel exchanged a quick look with each other before Dean tried to answer him. "Well, uh, you're the kid, Castiel is your dad and we're your uncles. So you're our nephew, I guess."

"Nephew," Jack repeated. "If you're my uncles, that means that Castiel is also your brother and not only Sam."

"Damned right," Dean said proudly. "Like our Bobby always said. Family doesn't end in blood. Cass has earned his status as our brother many years ago."

"Your brother," Jack repeated again.

"Yeah," Sam said.

"But, if Castiel is your brother, who's the middle brother?" Jack wondered.

"Castiel," Dean said.

"Dean," said Castiel at the same time.

Castiel and Dean looked at each other.

"Excuse me?," Dean said, offended.

"That's obvious," Castiel huffed. "I'm the oldest one in this room, of course I'm the oldest brother."

"Um, no you're not," Dean protested. "You can't always use age as a measure. You have to use logic."

"Uhh, what?" Sam looked confused. "Being the oldest one here makes being the oldest brother logical, so what are you going on about?"

"Siblings!" Dean said proudly. "Think about it. Sam, do you have any younger siblings?"

"No."

"No. So therefore you can't be an older brother, because you don't have any siblings younger than you. That makes you the baby brother. Castiel, do you have any younger siblings?"

"Yes, but-"

"Great! So you're not a baby brother. Do you have any older siblings?"

"Yes, but I don't see-"

"And that's my point. You have younger siblings, and you have older siblings. That makes you a middle child. Me, on the other hand, have younger siblings, but I have no older siblings. Therefore, I'm the big brother, Cass is the middle brother and Sam is the youngest brother."

Everyone sat silently, staring at Dean. It only took a moment for Sam to break the silence.

"You've really spent a lot of time thinking about this."

"Nope, no I have not," Dean denied. "But I'm right, huh?"

When he didn't hear any protests, Dean smiled, leaned back in his chair and sipped his victory coffee.