Sam startles himself awake from a dream in which he'd lost you to the Darkness. He feels around the bed and it doesn't take him long to realize it's empty. He rolls over to the edge so fast he nearly falls out onto the floor, but somehow lands on his feet. "[Y/N]?" he calls out into the dark. His heartbeat speeds up when there is no reply.
He hurries down the hall to your bedroom. The door is wide open, and he doesn't have to step foot inside to see that you're gone. Your bed is empty, your bag is gone, and his hoodie is folded neatly at the foot. His eyes widen as his fears come to light.
"Dean!" he yells, sliding to a stop at his brother's door. He pounds and pounds and barges in.
Dean grumbles and rolls over, blinking in the light spilling in from the hall. "What the hell, man?"
"Dean," Sam says, breathless. "I think she's gone."
The sleepiness leaves Dean's eyes in an instant as his whole body tenses. "What?"
"She's... she took her stuff. Dean... I think she's gone."
Dean's out of bed in the blink of an eye, pushing past Sam. He knows where to look for you; you're probably poring over some old books in the library, trying to learn as much as you can. That's all. They'll find you there and everything will be fine. Just like when he found you on the floor looking for anything you could get your hands on to save your friend.
They run through the hall, too fast to stop or turn without sliding in their socks. "[Y/N]!" Dean shouts as he catches himself on the door frame of the study. He scans every corner, every shadow. But you're not there. No.
"There's a note," Sam says, walking to the table. His arm is stiff as he reaches for it. He's afraid of what it might say. The three of you hadn't known each other long, but somehow you wound your way into his heart. He swallows the choking sob that threatens to betray his stoic face. Dean is by his side, looking over his shoulder as he reads. Sam clears his throat before he begins. "It says, 'Oh take your time, don't live too fast, troubles will come and they will pass. You'll find a woman and you'll find love and don't forget, son, there is someone up above.'" Sam turns the paper over, looking for more. "That's it? Song lyrics? What is this supposed to mean?"
Dean can't answer. He can't answer because if he opens his mouth, he will break, because he's thinking about sitting at the table with you, a bottle of whiskey, and that damned laptop playing that damned song.
Sam glances around the room for something more - anything more. He feels like another piece of his heart has been ripped out and tossed into the wind. He needs to do something. Sam Winchester can't just sit by and let you accept this insane fate... not if there's something he can do.
Dean calmly takes the note from his brother's hands, swallowing the jagged lump in his throat, wondering if you would have stayed if he'd told you he wasn't drunk when he kissed you... At least, not drunk on whiskey.