And now the light bulb's gone off

I've seen it in your eyes

And there's nothing there

There's nothing there

—Spoon, Written in Reverse

Reality uncoils like a kite string. Lucifer taught him that.

It was one of the things he fought against in the first moments after he fell, when he was holding tight to his own mind inside the blinding insanity of the cage.

He doesn't remember when it broke, only that it did. And that it didn't take long at all. He remembers watching the fragile thread uncoil and drift. He remembers feeling lost. Terrified.

And then Lucifer took hold of the broken thing that was Sam's mind and held it tight, guided it back together with a firm certainty as he rebuilt Sam's reality. Showed him how to rewind it each time Lucifer himself brought Sam to his knees with madness.

Always so patient. Always finding Sam's hand in the dark.

Tell me what's real, Sam, he would say, running the gossamer strand of Sam's mind through his fingers. Tell me what you know.

Pain, Sam responded automatically, without needing to think. You. Michael. The cage. D… He frowned. De…?

Only what you know. Lucifer pulled the string tight, securing it. Only what's real.

Sam hesitated only a moment before replying. This, Sam said, and he let go of the fragment of memory he'd been holding on to, of green eyes and comforting touch, whatever long-ago thing he might have known or hoped for. He let it go. Let it drift, unimportant.

Lucifer smiled.

When it broke a second time, amid shambles of the wall and the dark flood of memories threatening to overwhelm him, it was Dean who found him again.

Dean is real. I'm real. This air, this floor, this room, this world. This is real.

This time, instead of Lucifer coaching him, his reality came from Dean. It was a foundation that felt right, because Dean had been his one stable thing all his life, through every confusing transition and paradox.

He could believe Dean. He anchored himself to it, trusting Dean.

When he felt himself beginning to drift, he grasped for Dean's truth verified by the sharp, real pain in the palm of his hand, and he believed it.

With Dean's death, it all imploded. And it began to unravel. Like a string. Just as Lucifer had promised it would.

Dean couldn't be gone. Dean was stone number one. With no Dean, there could be no stone number one. With no stone number one, there was no one to free him from the cage. With no one to free him…

Lucifer leered at him from the shadows, the darkness of the cage he'd never left.

And Sam ran.

He didn't stop running for weeks, hiding in abandoned buildings and under bridges, breathless and panicked, afraid to sleep, afraid to close his eyes for more than a minute, terrified that he might lose Dean's reality and open his eyes to the reality Lucifer decided for him.

When he hit the dog, he almost kept driving, because that couldn't be real. Why would there be a dog in the road? Why would there be a road in the cage?

He pulled over and leaned his forehead against the steering wheel, pulling the confused threads together. Dog. Road. Impala. Driving.

No pain. Just driving.

The road was probably real. That meant the dog probably was, too.

He stumbled into the vet's office carrying the wounded animal and called out for help, then collapsed into a chair in the waiting room. He dropped his head into his hands, tears filling his eyes, so exhausted and traumatized that he couldn't think straight.

He felt a hand on his shoulder and looked up, cringing, expecting Lucifer, expecting punishment and pain, and instead found kind eyes and a sympathetic face. The woman sat down in the seat next to him.

"Are you all right?" she asked. She had a small pet carrier by her feet.

Sam opened his mouth and then closed it, not sure what to say. "My…" his throat felt rough. His voice was barely a whisper. He looked down at his hands. There was blood under his fingernails and he couldn't remember why. "My brother," he said. "He's dead."

It was the first time he'd admitted it, even to himself, and a swell of emotion broke over him. Because this was true. He could feel it. This was a true thing, it was a new reality. He could hold on to this. Dean was still stone number one. Even if Dean was dead. He could grasp onto that, still rely on Dean, believe in him. Even dead.

Sam swallowed hard and turned his face away as silent tears fell, and the kind older woman dug a tissue out of her purse for him.

Dean is dead.

He almost didn't answer the cell when it rang.

Dean is dead. I was trapped in the cage, but Dean got me out.

He breathed in, looking at the phone, reminding himself of the tactile reality and the physical connection between objects and sound. When the phone rang again after the long silence between rings, it startled him.

It shouldn't have been this difficult, but it was sometimes. Lucifer would have told him what he wanted Sam to see. Dean would have made him meet his eyes and focus until he could work out what was real.

He realized after another ring that the phone in his hand was actually the thing that was making his reality waver, and after another moment he realized why.

Dean's name was on the caller ID.

Dean is stone number one. Dean is dead.

This was a trick. It had to be a trick. Lucifer played tricks like this to make him think… to make it worse when he…

I was trapped in the cage, but Dean got me out. Dean is stone number one.

Cautiously, Sam pressed a button on the phone and brought it to his ear. "Sammy?" It was Dean's voice.

But Dean is dead.

Dean's voice was eager and insistent, and Sam couldn't help but feel the swell that rose in his chest at the sound of it. "Man, Sam. You're a hard one to get ahold of. What'd you do, drop off the face of the earth?"

Sam didn't answer.

"Sam, you there?"

"I'm here," he said uncertainly, not sure of the truth of it.

"I'm at Rufus' cabin. Come meet me, okay? I can't wait to see you!"

Sam felt an important part of his foundation slipping away, his trust in this reality irreparably shaken. He clutched the phone to his head trying to find where the thread is leading. "Y-you too," he stammered.

Dean is dead. But he's not. I was trapped in the cage, but Dean got me out.

Please, please, please no. It can't be.

Sam hung up the phone and hugged his arms to himself, drawing his knees in to his chest to make himself as small as possible on the mattress, thinking that this could be the cage. This could very well be the cage.

The closer Sam looked, the more certain he was that the edges of this reality were frayed, or perhaps a bit too sharp.

In a cautious breath, he whispered, "L-Lucifer?" and braced himself for the blow.