Sam looked up as he watched Dean enter the bunker followed by a boy who seemed not above seventeen years old. He frowned, glancing over as Cas walked up next to him, before he spoke
"Dean who's this?"
Dean flinched, as though he hadn't expected Sam to speak. He froze, causing the young boy to bump into his back. Both Dean and the nameless boy stared down at Sam, before Dean leaned.
"Right. Sorry Sam. Um...this is my friend. His name's Alastair. He's a hunter right Al?"
Alistair nodded, grinning.
"New to the gig. And honestly, from what I've heard from Dean it's clearly not the best life choice. I mean, the Mark of Cain?"
Dean frowned, turning to face Alastair.
"I never told you about that. How do you know about that?"
Alastair looked away.
"I don't really want-"
Cas chose this precise moment to interrupt.
"You've been tortured by Demons for information."
Alastair's mouth dropped open slightly, and he looked away. Dean watched him for a few seconds before he asked
"Why didn't you tell me?"
Alastair shrugged.
"I didn't think it was important. Dean you saw the way I was living. You saw how I had to live to survive! I thought you understand why I didn't tell you."
Dean looked to Sam for help, so the younger brother spoke.
"Alastair why don't you stay here with us for a while alright? We can help you train to be a hunter and maybe you can tell us what the Demons wanted."
Alistair nodded, and so followed Dean down the stairs into the bunker. As Alastair passed Cas however, the Angel grabbed the young boy tightly by the shoulder, and hissed in his ear
"I know what you are."
Alistair nodded, quickly shaking himself from Cas's hold and rushing after the brothers. Just before he left the room his whispered
"I know what you are too Castiel."