Castiel had great admiration for Dean Winchester, but he was beginning to wonder if he wasn't, perhaps, a bit oblivious.

"Sam does not look well," he said, because Sam did not. There were dark circles under his eyes and he seemed hunched in on himself. He looked even thinner than the last time Castiel had had occasion to observe the Winchesters closely, and Castiel was relatively certain that those muffled noises were poorly disguised, dry-hacking coughs. It was just him and Dean tonight; Sam was out getting dinner, or pie, or something. Dean looked up from the gun he was dismantling.

"What?"

Castiel held back a sigh. At times Dean's apparent lack of regard could be…frustrating. Sam assured him it was nothing personal, and it did not seem to be, but nonetheless. "I said, Sam does not look well," he tried again.

Dean shrugged, apparently losing interest. "Does anyone, these days?"

"I believe he may be ill," Castiel said. Dean went back to checking small metal pieces.

"Sam's fine," Dean said. "I'd know, okay?"

"But can you be sure," Castiel started to object, and Dean gave him an annoyed glance.

"Look, if Sam were sick, he'd be whining like nobody's business. That's what he does when he's sick. He hasn't said anything, so that's how I know he's fine. Leave me alone, Cas, I'm trying to concentrate."

Castiel was not entirely sure he was convinced. In the past year, he could not seem to recall Sam whining in his hearing once, though he was quite sure that in at least a few cases it might have been warranted. Perhaps it was nothing. After all, he still knew so little about humans.

When Sam returned, he looked pale, and Castiel noticed that he only pretended to eat. Then again, that might have had more to do with the quality of the food. Even Dean glared at it suspiciously.

"Jesus," he said. "What is this crap?"

"Sorry," said Sam, sounding unreasonably contrite, and was that a hint of a rasp? "It was all I could find that was open." He looked down at the plastic container and pushed his salad around with a fork.

"Aren't you hungry, Sam?" he inquired, finally, and Sam jumped a little, as Castiel had noticed he always seemed to do when spoken to by just about anyone. As though he were perhaps expecting something else. He wondered about that.

"What? Oh, uh, yeah," Sam said hurriedly, and picked up a forkful of leaves and stuck it in his mouth, and Castiel could see him trying not to grimace. "Just distracted, I guess."

Dean, meanwhile, was staring at his own dinner in disgust and appeared to have noticed nothing. Perhaps he would just have to handle this on his own.

~.~

In the middle of the night, Sam got up and vomited (very quietly) into the toilet in the bathroom. Castiel rose from his state of contemplation and stuck his head through the open doorway. Sam was folded on the ground with his cheek against the porcelain, his face pale and sweaty. He looked supremely miserable.

"Are you all right?" Castiel asked, because he knew that was the sort of question humans asked when they knew that things were not all right. Sam grimaced at him, though Castiel suspected it was probably meant to be a smile.

"Yeah…yeah, I'm fine. Something probably just didn't agree with me, happens a lot…"

"Would you like some tea?" Tea, Castiel knew, was known for its soothing properties. That sounded like something that might be necessary. Sam blinked at him, though, like he'd said something utterly foreign. Perhaps that was not how Dean would respond. He tried to imagine that, and decided it probably contained a lot of swearing and worried admonitions about pansies, though it was quite beyond Castiel what a flower had to do with anything.

"Um." Sam spat into the bowl and groped for the flush, pulled it down, and didn't move further. "I guess. Sure? Did I wake you up?"

"No," said Castiel truthfully. "I have been lying awake and thinking."

"Huh," Sam said, "Is that right?" He didn't actually sound very interested, so Castiel decided it was probably not a question that required an answer.

"I will go boil some water," he said instead. "Do you need…"

"Nuh," Sam said, and shoved himself up to his knees, though he wobbled so precariously Castiel almost grabbed him to steady him. "M'good." A flicker of worry, and, "Is Dean…"

"Still asleep," Castiel said, and noticed that Sam was trembling minutely. He narrowed his eyes, but went to set the water on to boil, and by the time he turned Sam had made his way into the kitchen and was sinking gratefully into one of the chairs. He was sweating visibly. Castiel sat down across from him.

"You are sick," he said, certain now. Sam shrugged one shoulder, and Castiel persisted. "For several days?"

"A bit," Sam said, after a moment. "I. Uh. It's…sometimes it happens. Nothing big." Castiel noted that he could hear a faint wheeze in Sam's voice. "It'll clear up."

"You do not seem to be getting better," Castiel said slowly. "You seem to be getting worse."

Sam looked agitated. His fingers drummed on the table. "I've had worse," he said. "Really. I just – uh." He stopped, and coughed into his arm, a nasty dry noise that made Castiel's borrowed throat cringe in sympathy. "—I. Don't want to hold anything back. Or anything."

"Dean is unaware," Castiel started to say, and was startled by the savagery in Sam's voice as he said, "Good." Castiel frowned.

"You will recover more quickly, I understand, if you rest."

"I don't have time to rest." Sam was shaking again. "Not right now. You get that, right?" He twitched.

"I," Castiel started to say, and Sam stood and smiled tensely.

"Thanks," he said, though Castiel was sure he hadn't agreed to anything. "I really appreciate it. I mean. I do. And you know, it's nice that you're worried, but you don't need to, or anything." And then he was gone, before Castiel could even remind him about the tea.

Sam was not up early the next morning, which meant Dean had to wake him, which put them both in a bad mood. Sam, Castiel observed, did not look any better. If anything, in the better light, he looked worse. He watched Sam rattle a few pills from a non-descript bottle into his hand and down them when Dean wasn't looking.

"I am going out," Castiel announced, and noticed that Dean looked annoyed and Sam looked relieved. He would have been hurt by that if he hadn't known that Sam was worried he was going to tell on him. Castiel was quite sure, having already tried that, that it would prove fruitless.

That left it up to him, and he was woefully ignorant about this kind of thing, but he had gathered what the Winchester brothers did when they were ignorant about something. Or at least one of them.

He went to the library.

~.~

"I would like to see your books on illness, please," Castiel announced to the librarian, upon walking inside. She looked up from her glossy magazine – Castiel could read the headline as "10 Sex Moves That Will Blow His Mind" – and stared at him for a moment.

"What kind of books?" She asked, just as Castiel was beginning to fidget.

Castiel had not considered that. "There are different kinds?"

He recognized that sigh. It was the one that Dean usually used when he thought Castiel was being stupid. "Yes," she said, feigning patience. "There are books on epidemiology, self diagnosis, specific diseases, general medicine…"

This was beginning to sound a touch overwhelming. Castiel considered attempting the use of one of the computers, and decided against it. Books at least he was relatively familiar with. He cleared his throat. "My – friend is sick," he said, finally. "I am not sure what to do to help him get better."

The woman was now looking around him as though expecting him to be accompanied by someone, so he provided, "He isn't here. Right now."

The woman frowned. "Ah. I, well. What is your friend sick with?"

Castiel contemplated that. "I don't know," he said, finally. "He has a cough and I suspect he is feverish, and last night he vomited. I am not very familiar with different types of sickness. Plagues are more familiar to me."

Perhaps that hadn't been the right thing to say, though he had intended it as a kind of joke. The librarian looked very uncertain now. "It sounds like some kind of flu," she said, edging back from the counter as though he were, perhaps, dangerous. "There's some…over the counter medicines, fever-reducers. Fluids are good? And rest, rest is important. Other than that…sometimes Saltines are good for nausea?"

"Is there a book?" Castiel asked hopefully, because he wanted to be sure – but he stored that away. Saltines. Whatever those were.

"I can probably find something," the librarian said, and scuttled off. She returned with a couple books which she shoved at him with a plaintive 'have a nice day!' and Castiel retreated to a table to read.

~.~

He returned to the motel armed with Saltine crackers and knowledge, and began his project. He placed the crackers in plain sight and sat down to wait. Both of the brothers were out.

When they returned, Dean looked at the counter and frowned. "Who got the Saltines?"

"I did," Castiel said, trying to give Sam significant looks. Sam did not seem to realize, so Castiel got up and got two glasses of water and shoved them at Sam and Dean both.

"What's this?" Dean asked. Sam was just staring blankly at his as though he'd never seen such a thing before.

"It is important to stay hydrated," Castiel parroted from one of the books, and Dean looked at him like he was an alien.

"Every time I think you can't get any weirder," he muttered, but he drank the water. After a moment, so did Sam. It was a minor triumph, but Castiel was a soldier, and he knew to treasure every victory. "Want some Saltines?" he offered, and Dean shrugged and took a handful.

Sam demurred and retreated hastily. And that was why the victories were so important. Well, he couldn't expect too much too quickly.

The next phase of his plan was trickier, but fate worked in his favor and Dean was heading out to weasel people out of their money, and told Sam to stay behind and research. Castiel had gathered that this was more than a little illegal, but it was also not his problem.

Dinner was a strange affair, and Castiel was not entirely certain his attempts to keep a continuous supply of water glasses in front of Sam went unnoticed. His reminders that hydration was important and the human body was made of 78% water were almost certainly less than subtle, judging by Dean's indignant, "Dammit, Cas, are you trying to make me pee?"

By the end of the whole thing, Sam was watching him suspiciously out of bleary eyes, and Dean was just plain watching him.

He went, though.

Which left Sam and Castiel staring at each other.

"I'm going to go do some research," Sam said, and started to lever himself painfully out of the chair. Castiel folded his hands on the table.

"No, you're not," he said placidly. Sam turned his head slowly and gave Castiel a long, slow, and very slightly disconcerting stare. Then it drifted out of focus, and the effect was lost.

"…sorry, what?" Sam said.

"You need to sleep," he said, firmly. Sam was staring at him with something between bewilderment and panic.

"…Cas?"

"You are unwell. I have read books," Castiel said stubbornly. "You require sleep. Dean will not return until late, and it will not be unreasonable for you to be asleep then. Also, your laptop is in the trunk of the Impala where it is entirely useless to you."

Sam's mouth opened, then closed. Castiel could not help feeling a bit smug.

"I can't sleep," Sam said after a while, in a small voice, bleary and a little plaintive. He was shivering again, and Castiel made a note to get the extra blanket out of the closet.

"I have drugs," Castiel said.

Sam blinked, and then made a strange sound it took Castiel a moment to realize was half cough, half laugh. "You have no idea how funny it is to hear you say that," he said, and then broke into a true coughing fit that had Castiel worried he was going to choke.

He rubbed Sam's back awkwardly.

"Cut that out," Sam said when he could breathe again. "It's weird."

Castiel felt momentarily disappointed. "It doesn't help?"

"Unh. Not really. Don't tell Dean, though, it's the only way I can get any touchy-feely time." Sam made a strange hiccupping noise.

Castiel did not quite understand that, and settled for a stern, "Go to bed."

"Sure," Sam said, and got up. And just as quickly nearly fell over. Castiel caught him. "Wow," he said. "I really…feel like crap." Castiel frowned. He could feel the fever on Sam's skin.

"Very well," Castiel said. "That is it."

He half carried, half dragged Sam from the kitchenette to the bed that seemed to belong to Sam, and dumped him in it. But gently. Sam curled up in a fetal position and shivered. Castiel went to find the medicines that he had purchased, and after careful reading decided two of the fever-reducer-pain-relievers should be sufficient. He poured them into his hand, got a glass of water, and offered them to Sam.

"Take these."

Sam looked at him for several long moments, and finally reached out and took the pills, popped them in his mouth, and swallowed awkwardly before slumping back down. Castiel began pulling the covers out from under the younger Winchester, and Sam obligingly rolled over and around. After much labor, Castiel pulled the sheet up over Sam's shoulders and tucked it in.

"Do you need something to help you sleep?" he asked. Sam's eyes emerged from the heap of blankets to glare at him.

"Don't drug me, Cas."

Castiel was momentarily taken aback, both by the nickname and the tone of voice. He did not, however, let it last. He suspected that Sam was not entirely in his right mind. "I could sing," he offered.

"Oh god," Sam said, but it did not sound worshipful. He closed his eyes.

Castiel settled for humming. To his utter surprise, Sam's shivering actually subsided, and he started to sleep. His skin was still hot and he would not be cured in the morning, but maybe he would be better. It was a start.

Not bad, Castiel allowed himself. Not so bad.

~.~

Dean returned late, as Castiel had predicted, and Sam had only woken up once. Castiel had poured two glasses of water down his throat before letting him go back to sleep.

The elder Winchester seemed slightly inebriated as he stumbled in and looked at Sam, frowning. "You know," he said, finally. "I think Sam might be sick."

Castiel paused. Looked at Sam, sweaty curls of dark hair on the white pillow. He cleared his throat.

"Really?" he said.