Author's Note: Yes, yes, I know, I should be updating all my other stories and I will, but I had to post this! I've missed writing Sam/Castiel friendship fluff and this popped into my head and it wouldn't let me go. Major spoilers for "Man's Best Friend with Benefits" in here! There's a reference in here that Castiel makes to one of my other stories, "Something to Believe In" and while you don't need to read that to understand this piece, it will help you get the reference. There's no slash in here, only shameless friendship fluff. Anyways, please enjoy!

He hadn't wanted to keep it from Dean.

He had hidden things before from his brother and it had always led to disaster and in one awful case, it had led to the Apocalypse. So, for the record, when he had noticed that he was coughing up blood, his first instinct was to tell Dean. Dean deserved to know and frankly, if their positions had been swapped, Sam knew he would've been pissed if he had found out that Dean had been keeping things this important from him. So, for the record, he had wanted to tell Dean.

But he didn't.

He had just gotten Dean to trust him to do the rest of the trials. If he confessed what the trials were taking out of him physically, the eldest Winchester would throw a fit and forbid Sam to finish the trials. Screw them, Dean would shout, you're more important! While the youngest Winchester was happy that his brother still cared so much for him—especially after their rocky start once Dean had gotten out of Purgatory—he knew that the gates of Hell had to be shut. And yeah, Sam didn't want to die. He had meant what he said to Dean—this wasn't a suicide mission for him and he did see a light at the end of this tunnel. Whether he'd still be alive to see it though, he wasn't so sure. So, Sam kept quiet and thankfully, there hadn't been anyone coughing outbursts.

Until tonight, that is.

Dean had stepped out of their "Batcave" to go get some food and as soon as he was out the door, Sam had doubled over, coughing threatening to tear him apart. Forcing himself to move to the bathroom, he glanced at himself in the mirror.

Blood.

Blood trickling out of his mouth and splattering the porcelain sink below. Blood filling his mouth with that awful coppery taste that signified internal bleeding. Sam didn't need the blood to tell him what he already knew. The trials took a toll out of the chosen warrior. He thought back on all the heroes of ancient myths and tried to figure out if at the end of their trials if they perished or not. His mind was fuzzy though and the coughing was starting up again and there was blood, too much blood—

"Sam." A soft hand was placed on his back and suddenly, the fit left him. Spinning around, Sam found Castiel standing before him, the angel regarding him with a sad and solemn expression.

"Cas," He breathed, a bit startled but also relieved. They hadn't seen the angel since he had cryptically taken off to Heaven with Samandriel. "How did you—?" The youngest Winchester was winded, but gestured vaguely to the bunker.

"There is no angel proofing."

"Ah." Sam mumbled, because yeah, the Men of Letters probably hadn't figured out angels existed so why would they protect against something that wasn't real? He calmed his breathing and with a towel, wiped the blood away. His heart pounded in his chest and Sam wondered dimly if it was from panic or the physical repercussions of the trials.

"You are ill," Castiel stated calmly. "Why have you not brought this to Dean's attention?" Sam shook his head wistfully.

"Dean would just try to stop me." He answered.

"From?" Castiel's head tilted slightly to the side in confusion.

"Closing the Gates of Hell." The angel's eyes widened and shock graced his expression for the briefest of seconds. Then, it was eclipsed by rage and anger.

"You must stop, Sam," Castiel growled and Sam felt himself involuntarily back up, only to hit the marble counter. "The trials will kill you, even if you manage to complete them."

"Cas, I have to—" He protested weakly.

"No, Sam, you do not!" Castiel shouted and it was the first time that Sam had ever seen the angel in such a state of distress. Castiel never got emotionally worked up over much and seeing him like this—furious and worried—reminded him briefly of Dean. Maybe his older brother had rubbed off on the angel more than even Sam knew. "Why have you not told Dean?"

"Like I said, he would only try to stop me from finishing them—"

"With good reason," Castiel hissed, fury coming off him in waves. "Sam he deserves to know. If you were in his place, you would be furious if you found out he was hiding something like this from you—" Sam simply nodded his agreement. There was no point in arguing over a point he knew to be completely true.

"Better me," He whispered. "Than Dean."

"Sam—"

"Cas," He started quietly, letting himself lean more against the counter. He was suddenly winded and all he wanted was to sit down and catch his breath. "Closing the gates of Hell is the endgame. We do that and—"

"You'll die." Castiel interjected softly, eyes glazed over with grief.

"How do you know that?" Sam questioned gently. "No one has ever attempted these trials before."

"That is untrue," The angel contradicted. "Over the years, there have been others. All of them have died in the trials or have succumbed to the physical effect of the trials." Sam shut his eyes briefly and forced his emotions under control. Death wasn't something he had wanted to experience ever again, but if it meant closing the gates of Hell, if it meant ridding the Earth of demons, then surely his life was worth little compared to all the lives that his actions would save?

"I've already completed the first trial, Cas," Sam informed the messenger of Heaven quietly. "And I'm going to do the rest. And if I die . . ."

"Dean will follow you," Castiel told him, eyes locked onto his gaze. "Surely, you know that? He barely survived the time you spent in the Cage. If you should succumb—" Sam held up his hand, wanting the angel to stop. He had seen Dean die too many times and he didn't want to think about his brother willingly ending his life just because Sam had perished. Dean had so much to live for, even if he didn't see it now.

"Castiel," Sam summoned up his strength and willed his voice to be strong, his tone calm and yet full of hidden confidence. "I have to do this."

"But Sam—"

"You know that if I don't do this, Crowley will just come up with some scheme to doom the world, right? And even if he doesn't, a lot of people and angels will be hurt." Castiel nodded his head, but opened his mouth to speak. Sam cut him off quickly. "So, I have to end this, Cas. I'm the only one who can and if I die—"

"Do you value your life so little that you are willing to throw it away?" The angel yelled and that struck something within Sam. Anger coursed through his veins igniting fury that had been long held dormant.

"Dammit, Cas, no!" He growled, eyes stinging slightly. He willed the tears away though. He wasn't some child and he wouldn't cry over this. "I want to live, okay? I don't want to give up my life!" At this outburst, Castiel's expression softened ever so slightly. It appeared as if he was almost ashamed for saying such things to Sam. "But if me dying means that no demon will ever ruin a family again, then I'm willing to die for that."

"Sam . . ." Castiel's voice trailed off as if he couldn't come up with anything more to say when Sam was so resolute.

"I mean, if the gates of Hell had been closed 50 years ago, my mom would have lived. I would've known who she was." A lone tear snaked down his cheek and Sam furiously wiped it away. It seemed like everything had always come back to the memory of Mary Winchester. John had given up his life to avenge her; Dean viewed her as a goddess who had once walked the Earth and Sam? Well, he knew nothing of her aside from a few pictures that he had been lucky enough to see. He had never heard her voice aside from that one moment in Heaven and even then, he hadn't had a chance to interact with her. The only words he had remembered her speaking to him were, "I'm sorry." If Hell had been closed, Sam would've gotten to meet her and know what it was like to have Mary Winchester in his life. If Hell had been closed, Jessica wouldn't have died either. They would've gotten married and had a few kids by now. Dean would've been an uncle with perhaps a wife of his own. They could've had a normal life if Hell had been closed.

Sam wouldn't risk ruining other people's lives by running away from the trials now. No, he would see this through to the end, even if all that awaited him was certain death.

"Sam," Castiel spoke softly, voice barely rising above a whisper. "You will remain resolute in this matter?"

"Yeah." Sam told him and the angel nodded, his mind seemingly made up.

"Do not give up hope then," The youngest Winchester regarded him oddly. Hadn't the angel been the one to say that only death awaited him? "I shall search and see if I can find a way to help you."

"Cas, you don't—" A sharp glare silenced Sam.

"You once told me that family was more than blood," He nodded, dimly remembering the conversation they had had around Thanksgiving just before some rogue hunters had shot Sam. That had been almost three years ago though! What was the angel getting at? "And as such, I will not give up on helping you, Sam. You and Dean . . . you are my family." The angel smiled, the sadness in his eyes replaced with determination. "I will not let you perish."

With that, he was gone in a flutter of wings. The bunker door opened and Sam could hear Dean pushing it closed behind him.

"Sam?" Dean called and the youngest Winchester nodded to himself. No more hiding. It only led to problems down the road.

Tonight, Sam was going to tell Dean what was going on.

And together—because they were stronger together—they would figure something out. Castiel was right; Sam wasn't going to go down without a fight.

"Thanks, Cas."

With that, he went to face his brother.

Author's Note: Yay for shameless friendship fluff! Did you enjoy it? Please review if you have a second!