A/N: This story is slightly AU as Castiel reveals some information to Sam that Dean doesn't tell until a later episode. However, I felt it plausible as I didn't think Sam's reaction was a surprised as it could have been (I'm blaming the demon blood for that one).
The screaming has been going on for almost 12 hours. Sam knows he's being selfish in the light of more evidence of his brother's obvious pain, but part of him just wishes for a few hours of silence. He's downstairs right now getting more ice while Bobby tries to calm Dean upstairs. Sam had brought Dean here a few days ago when the sickness began, but Dean has only continued to worsen. Sam figures it has something to do with the fact that Dean barely sleeps anymore due to the Hell nightmares that have been increasing in intensity since their little meeting with Alastair.
Sighing with resignation, Sam gets the needed ice and washcloths as well as some cold water to bathe Dean's burning body with. He heads back upstairs for another round of trying to comfort his brother. Just as he arrives, Dean's screaming tapers down to whimpers. Sam knows he should feel compassion as his first emotion, but as it's been since Dean first died, Sam's first emotion is consuming rage. Lilith will most definitely pay for each scream she tore from Dean's throat.
"Here's the ice" Sam says quietly to Bobby who is sitting on the bed with Dean trying to calm him down. Bobby's eyes are haunted, but he resolutely takes the ice and wash cloth and begins making makeshift ice packs under Dean's armpits. They've stripped Dean down to a pair of sleep pants and a thin blanket to try to reduce the raging fever. Dean coughs wetly and rolls his head mumbling as Bobby packs the last ice pack under him. Sam wrings out a cool washcloth and begins wiping the sweat off Dean's face. "Go take a break," he gently tells Bobby. "I've got him."
Bobby nods and heads downstairs, saying something about getting a drink and to call him if he's needed. Sam nods absently as he registers again just how hot and flushed Dean is from the fever. He knows that Dean probably needs a hospital, but for the life of him he can't figure out how he'll get Dean out of a psych eval when he starts screaming about hell and demons.
Sam starts when he notices Dean's foggy green gaze on him. Dean laughs sinisterly and Sam knows instantly that he's not lucid.
"So here you are again," Dean says, again laughing without mirth. His voice is raspy from both the coughing and the screaming. Sam is honestly shocked he can even speak.
"How long will you keep coming here you son of a bitch?" Dean tries to lunge at Sam, but he's too weak and Sam easily pushes Dean back.
"Ssh" he soothes Dean as he resettles the ice packs and avoids eye contact with Dean. "You aren't in hell anymore, Dean." Sam rewets the washcloth and finally looks Dean in the eyes. "You're back, remember?"
Dean scoffs. "What, you think I wouldn't know my real kid brother? Good imitation, but you've got Sammy all wrong."
"Oh yeah?" Sam says casually. "How's that?"
Dean looks at him and starts to reply when he coughs again. Sam helps prop Dean up so he can expel the mucus and get some water.
Sam settles Dean back down again, but he seems to have lost his train of thought from earlier. He's back to restlessly throwing his head back and forth and letting out quiet moans. Sam hopes he stays that way since it will be better for everyone if Dean can finally get some rest.
Sam is only now coming to grips with the fact that Dean remembers hell. Part of him is royally pissed at his brother for trying to hide that information from him. A flashback during the middle of a hunt could be the end for both of them. Sam realizes that he should feel more sympathy than anger, but lately anger is his most available emotion. He would like to blame it on Lilith and Dean's trip to Hell, but deep down he knows that part of it is the demon blood he keeps consuming.
It's a small price to pay for Dean's safety. Dean has returned to him, but he's not the Dean Sam remembers. This Dean is warier, and seems to need more protecting. He's not cowardly, but he's no longer brash and cocky. He's still Dean, but at the same time, he's not Dean. Sam knows it's selfish, but he wishes he could go back to the time before demon blood, back to the time before the damn deal was struck and his life was returned to him.
Dean shifts and moans lightly before coughing wetly again. Sam pulls him up and gives him some more water. Dean drank gratefully, as if he were afraid he would never drink again. "Easy, Dean," Sam admonishes, pulling the water away and settling Dean back down again.
"He drinks because he fears he won't have another chance," said a voice from behind Sam. He whirls around to see who was in the room with him. Sam saw Castiel standing by the window, looking out as if he didn't want to watch Sam and Dean.
"What do you mean?" Sam asked cautiously. Dean mumbles something and Sam set his hand on his shoulder, still standing protectively beside Dean.
"In hell," continued Castiel, "there is no water."
Sam swallows convulsively at the confirmation of another form of torture Dean had gone through. It shouldn't surprise him really though. This was something that was found within the Bible.
"Why are you here?" Sam asked curiously.
"I needed to see how ill Dean was," Castiel said dismissively.
"Can you heal him?" Sam asked eagerly. "We could get back on Lilith's trail and…"
"You have grown to value the hunt over your brother," Castiel admonished strictly.
Sam gaped for a minute, knowing Castiel had a point but not wanting to admit it. "That's not true," he finally settled on denying. "But we have to catch her before she can hurt Dean again."
"The one hurting Dean the most right now is you," Castiel said with frustration, finally looking at Sam. "We thought that Dean would be able to turn you from your abominable ways. It seems your heart has grown too hard for even that."
"How dare you-" Sam started but Castiel interrupted.
"Dean has been through more in the last few months than you can possibly imagine. He suffered years of torture, and yet you call him weak. You are eroding everything about him that you value all in the name of your hunt," Castiel spat the last word as if it were poison. "You need to rearrange your priorities."
Dean coughed again and Sam looked back at him. He gasped in horror as Dean's skin seemed to bubble away leaving a raw, charred Dean behind. "Dean!" Sam shouted and reached out to touch him. Blood began pooling from different places on Dean's body, innumerable wounds that could not be fixed. An echoing cry of "Sammy" filled Sam's brain so that he couldn't tell if Dean was really screaming or it was just a memory.
Sam gasped as the influx of images and Dean's scream left him. Dean now appeared back to normal, although he was sweaty from the high fever. Sam turned his gaze to Castiel who was glaring at him accusingly.
"That's what Dean went through for the last four months?" Sam asked with horror.
"That's what Dean went through for the last forty years," Castiel corrected.
"What?" Sam asked with surprise. "Forty years? Dean's not even forty years old."
"Every month up here is a decade in Hell," Castiel sneered at him. "Your brother was tortured for nearly half a century, both physically and mentally. He held out longer than most could have, but when they broke him…" Castiel cut himself off as if he had said too much. "We need the two of you working together. Fixing each other."
Sam was still too horrified by the ramifications of what Castiel had just said to fully understand everything. His mind stuttered to a stop and he reached down and grasped Dean's hand without realizing it. Cas was gone by the time Sam looked up again. Burdened with the weight of Dean's pain, Sam bowed his head next to Dean's and wept.