Little Destiel moment in this one, hope that's okay.
The three boys stared in awe at the room they were now in. The circular dome was easily fifty feet in diameter all the way up. Covering the walls were doors, each one looked exactly the same, and didn't go any higher then ten feet tall.
A girl stood in the center, smiling. She had sparkling blue eyes and long coffee hair tied up in a ponytail on her head, her skin glowed creamy pale in the soft light that shone down from a small circular window at the very top of the dome. She was wearing tight gray yoga pants and a super long sleeved pale blue shirt, with brown combat boots.
"Hey boys." she said, her voice was soft and melody, like Cinnamon milk.
Camilla clapped a stunned Castiel on the back, "I think they're a bit overwhelmed."
"Ah, of course," the girl said, smiling, "Camilla would you mind showing them to their room?"
"Not at all, right this way boys." Camilla said, turning to another door.
"N-no way." Dean said, finally finding his voice again, "not until you tell us what the hell is going on."
Camilla and the girl exchanged a glance and the girl nodded, "Camilla will answer all your questions." She said.
The three boys followed Camilla apprehensively to another door, but when Camilla opened it there was no portal beyond, only a room, identical to Deans in the bunker. Accept the bed in the middle of the room had split into three different ones.
The boys walked in after Camilla and she closed the door behind her, walking past them to sit on one bed. Castiel stayed standing, but Sam and Dean sat down across from Camilla, but, Camilla thought with a smirk, Dean sat on the edge, closer to Cas.
"So," Camilla broke the awkward silence, "what do you boys want to know?"
"Where are we?" Sam asked immediately.
"This is the center." Camilla said, as if that explained everything.
"And that would be…?" Dean said.
"Your world isn't the only one out there Dean," Camilla explained, "there are hundreds of other worlds, with heroes just like you and Sam."
Castiel looked at the floor, "and Cas of course." Camilla said, smiling at him.
"Yeah, we know about that, we've been to one of those before." Sam said, frowning.
"No, you came to the real world, our world." Camilla said with sigh, "the spell Balthazar used was ancient, old enough, in fact, to break through the world's."
"I'm not following." Dean said, "what do you mean the 'real world' our world is real."
Camilla looked down, "no, Dean, it's not."
Castiel frowned at her, "what do you mean?"
Camilla sighed, "your world is imagination, it was created by the hopes and dreams of thousands of people believing you were real, that power is unlimited and boundless, it literally turned fiction into reality."
"So," Sam face lit up with realization, "our lives are just fiction, those books are our lives?"
Camilla shook her head, "your lives are a television show, and you have thousands of fans around the world, not to mention in your own world."
"What?" Dean said.
"Those books by Carver Edlund, have you ever thought about how many people might have read those?"
Understanding flashed on the boys faces, and Camilla smiled, standing up.
"Now, that's enough excitement for one day, you kids get some sleep, I'll talk to you in the morning."
Camilla walked to the door.
"Wait," Cas called, "who was that girl out there?"
"She's my mother." Camilla answered, without turning around, and walking out the door.
Sorry this one is really short, it's mostly just for the explanation, give a review if you have any questions.