Sam comes to consciousness slowly. As he becomes aware of things—he's lying down, his head feels heavy, like he's medicated, he can smell disinfectant and fresh linens—he opens his eyes. It takes him a second to glance around and another second to remember why he's in a hospital.

He'd only gone unconscious for a few minutes back in his apartment, but when he'd woken up, the man from the bar was nowhere to be found and he could hear sirens outside. So Crowley had called 911 instead of just driving Sam to the hospital, which was only a few minutes away.
He had drifted in and out of consciousness after that, sometimes sleeping more than blacking out, but he must have gone out—or been medicated—before they got him situated in the bed, since he doesn't remember being here before.
He carefully sits up, expecting pain in his side, and slides up so he can rest against the pillows. He only gets a slight tightness where his wound is. He wonders what painkiller they must have him on. Raising his right hand to rub his eyes, he sees that it's wrapped in a white bandage and he can barely move it. He uses his other hand instead.
Sam starts when he opens his eyes again, jerking back hard enough he hits his head on the wall behind him.
Crowley is standing at the foot of the bed.
Sam winces and rubs the back of his head. "How'd you get in here? You weren't here, like, a second ago."
"Doesn't matter. How are you?" He asks in the kind of tone that says he really doesn't care.
"I—I'm alive. Please tell me you're here to explain what the hell happened."
"You're in luck," Crowley says, raising his eyebrows. "I am." He steps to the side of Sam's bed and holds out a pair of glasses. "Put these on."
Sam frowns. "I don't need those."
"Yes, you do. Put them on."
Still confused, Sam takes the glasses and starts to put them on.
"Don't hit your head again," Crowley adds as an afterthought.
The glasses slide in front of his eyes and Sam jumps again. This time, he gives a strangled yell and presses himself back against the bed frame, pulling his knees toward his chest to get as far away from what he sees as possible.
It's some kind of dog, but it's massive and smoking and has red eyes like pools of blood. He can see it, yet can't fully make out its form, as though it's a wavering mirage.
He yanks off the glasses again. "What kind of stupid trick is this?"
"It's not a trick," Crowley says, as calm as Sam is perturbed. "She's a hellhound."
"A what?"
"Hellhound. Her name is Juliet and she's the one who nearly killed you. Those glasses have been scorched with holy fire, that's why you can see her."
Sam cautiously slides the glasses back on, sees the hound, and immediately pulls them off again. "Why are you showing me this?" he hisses. This must all be some insane, drug-induced dream.
"You wanted answers," Crowley says. "I thought I owed you that much."
Sam puts his head in his hands, rocking back and forth slightly. "I'm going insane. None of this makes sense." He looks back up at Crowley and tries to take a deep breath. "Why were you there? Why did you save me?"
Crowley considers for a moment, but he doesn't seem to be pondering the answer, he has the look about him as though he's constructing a lie. Then he shrugs. "Because I sent the hellhounds after you."
Sam stares at him. He blinks. "How does that thing exist?" Crowley's response had gone in one ear and out the other.
Crowley rolls his eyes. "She's mine. From hell. I'm a demon, Sam."
"What." It's not even a question; it's flat-out disbelief.
Crowley blinks, and suddenly his eyes are as red as the hound's.
Sam shakes his head. "No. This is ridiculous. You can't expect me to believe any of this."
"How else do you explain it, Sam Winchester?" He blinks and his eyes return to their normal shade of brown.
Sam opens his mouth to say something, then stops. He frowns. "You've said that before. My full name. You said it the last day at the bar. How do you know?"
Finally, Crowley's calm is very slightly ruffled. "I…It's a long story. But I know about you. I know where you live—obviously—I know about your dog Riot, I know about your girlfriend who recently left town, I know you were adopted as an infant and never knew your real parents."
Sam is left speechless, his mouth slightly open. "I—how—why—that's—that's creepy. W-why do you know all that?"
"Like I said, long story. But I am a demon after all, and the King of Hell at that. I have resources."
"The King of Hell? What does that even mean?"
Crowley seems to be getting increasingly exasperated, but Sam isn't sure what else he expected, with stories like this.
"I'm a king. I run hell. Why else do you think I can command a hellhound like this?"
Sam swallows and puts the glasses back on. The hound has curled up on the floor now and, despite the wavering and smokiness, looks strikingly like a normal dog. "So there's a hell."
"Obviously."
Sam takes a moment to digest this, but at this point everything's getting so over-the-top that it doesn't take long. "Okay. But—why did you want to kill me? You said…you said you sent that—her—to kill me? And then saved me? I haven't…done anything."
"Exactly."
"Okay…?"
"I was going to have her kill you, but I realized you weren't at fault." He eyes Sam for a moment. "I thought you might have been the reason Dean left."
"What? What does he have to do with this?"
"Everything. Dean's a demon, like me, but not exactly like me. I'm a demon because I died as a human, was sent to hell, and had my soul warped and corrupted until I became a demon." He glances at Sam's horrified expression and adds, "That's normal. Dean, on the other hand, rather had…demonness…forced upon him. He's more volatile, more susceptible to emotions. He started acting different right after we visited your bar, and once you spoke about him as though you knew him—despite my efforts to ensure you two didn't have a meaningful conversation—I became certain you were the reason he'd changed."
"And…and you were going to kill me for it."
"Well, I figured once you were dead, Dean would eventually come back and we could continue running hell as before."
Sam glances around the room, shaking his head. He runs his hands through his hair to push it back from his face, then lifts the glasses and rubs his eyes. "Why save me, then?"
"I realized I was wrong. It wasn't you, it was an angel."
"Oh, good," Sam says vaguely. "An angel. But why did you care? You were gonna kill me on a hunch, plus you're a demon. Doesn't that mean you're, like, evil?"
"Of course it means I'm evil," Crowley says as if he's just been insulted. "But even evil has standards. Besides, we had talked before and…I don't hate you. So I stopped Juliet. Simple as that."
Sam shakes his head again. "Nothing about this is simple." He puts his head in his hands again and speaks without opening his eyes. "So you're a demon from hell. In fact, you're the King of Hell and you wanted to kill me because you thought I convinced your…demon friend?…to stop talking to you. Then you found out—somehow—that it was actually an angel who did it, so you decided to come stop your…your hellhounds from tearing me to pieces."
"See? Simple."
He sighs. "Why did you bother telling me all this?"
"What would you have thought if I hadn't? Humans have a tendency to convince themselves they're insane. Or lie to themselves."
Sam gives a hollow laugh. "I'm already insane, Crowley! I mean, I actually believe this ridiculous story. Hell, you're probably not even here right now and I'm delusional or dreaming."
Crowley steps a little closer. "You're not delusional, Sam. All of this has been real. You weren't delusional when you got attacked. But the wounds are real. How do you explain getting torn up by something you can't see?"
Sam sighs again and looks at the canine-like creature curled up on the floor. "Hellhounds."
"I can prove all of this to you if you still don't believe me."
"How?" Then he frowns suspiciously. "Wait. How?"
Crowley raises his eyebrows and nods.
"Hell? You want to show me hell?"
Another nod.
"No. Dear god, no. I don't—I don't need proof. And I certainly don't need to take a trip to hell with a demon."
Crowley shrugs. "Your choice. I suspect you couldn't deny the reality of all this if you went. If you still think you're insane in a few days…your bad."
"No. Still no. I think I've had enough of…all of this for a day."
"I gave you your answers. Happy?"
Sam shakes his head. "Not really. But…thanks for not killing me. I guess."
The demon lifts a shoulder and looks down at the hellhound. "Come on, Juliet."
Sam watches the hound warily as it stands, but it seems to have no interest in him. Since he can see it, he remembers he still has the glasses on and pulls them off. They probably look ridiculous.
"Hold on," he says before Crowley can leave. "What—what am I supposed to do now? I mean, demons, angels, hellhounds, hell? What can I possibly do now that I know all this?"
"Be a good boy, pray a lot, and hope you don't end up in my domain?" he asks with a smirk.
Sam stares at him.
"I don't know, I'm not a human," he says, rolling his eyes. "I knew about demons practically from the time I was born. Figure it out."
"Thank you, that's very helpful. Crowley," he says as the demon looks like he's going to leave again. "You tried to kill me, but you also saved my ass, so no one's indebted to anyone. But for my own sake, is there…is there a way I can contact you if I run into any of this stuff again?"
Crowley raises his eyebrows and one corner of his mouth turns up. "Did you just ask for my number?"
Sam feels his cheeks grow warm and he looks at the bedsheets in front of him. Dammit, you couldn't have said that a little better? "No. Well, I just—"
"Here," Crowley says, pulling a small notepad and pen out of his pocket and scribbling something down on it before setting it on the table beside Sam. "They looked good on you, by the way," he adds with a small nod to the glasses in Sam's hand.
Then he disappears right in front of him.