A/N: I was listening to Dean's Lullaby on repeat while writing this and I got extreme feels. I hope you like it! Disclaimer: I do not own Supernatural.

"Cas...Cas, will you wait a minute?!" Sam said, grabbing the angel by the arm, "What had gotten into you?" Castiel glared at him, practically seething with anger. Sam raised his eyebrows and squeezed the angel's arm gently. Some of the tension eased from the angel's shoulders. "Talk to me," Sam said. He hated that Cas was upset and desperately wished he had seen what the angel had seen.

Cas took in a deep, shuddering breath and let it out slowly. "That mirror is a rift. It is keeping the Dean from the other dimension trapped and is using him to find a way to feed itself. It wanted to eat me. It showed me...Dean being tortured," he trailed off, clenching his teeth.

He turned his head away and glowered at the floor. Sam sucked in a breath; he hadn't realized just how serious the situation had been.

"Cas, I-,"

"I can feel him, Sam,"

Sam jerked back, as though he'd been slapped. The note of sorrow in the angel's voice was enough to snap his heart in half.

"You can what? How?" Sam asked. Castiel sighed and rubbed at his eyes with his fingers. He suddenly looked exhausted in every sense imaginable. "The other Dean explained to me...that he and our Dean have a link. Well, because of this link, I can feel everything that Dean feels.

"I believe that it has something to do with the bond we share. When I pulled him from Hell, I left a portion of my grace within him. Because of that, I can still communicate with him," Cas said. Suddenly, his shoulders slumped and he sighed.

"I should have been there when you two went on the hunt. I could have prevented this from happening," he said, "I've failed you both again. I am an angel, Sam. I should not need a human to remind me of my abilities. I should have used them sooner. If I had, Dean might be here with us." Sam frowned; this wasn't like Cas at all.

Then again, Castiel hadn't been acting like himself even before Dean had been thrown into the mirror. There seemed to be something on his mind- something that he wasn't ready to speak about. Sam put a hand on the angel's shoulder and patted it in what he hoped was a comforting gesture.

"I feel...," Cas whispered, "I feel like a part of me is missing. My chest always feel heavy, like I can't breathe, and my eyes are always stinging, but tears never come. Sometimes, if I see or smell something that reminds me of Dean, pain bursts into my chest like someone stabbed me with an angel blade. I've felt such things before, but I never knew exactly what they meant."

Sam bit his lip and looked down at his shoes. He had known that the angel cared for his brother; now he knew just how much. "You're experiencing heartbreak," he explained. Cas looked up at him with squinted eyes and frowned in confusion. "My heart is very much intact. It is not injured," he said. Sam resisted the urge to sigh again; instead, he shook his head and spoke to Cas in a softer tone.

"Your heart isn't physically broken. It's emotionally ripped. See, because you love Dean, your brain registers him missing as a loss- as though he were dead. You miss him, Cas. I know because I miss him, too. But for you it's different. I miss him because he's my older brother and we've been through everything together. He's a lot more to you than just a best friend, isn't he, Cas?" he said. Castiel went silent, ducking his head to avoid Sam's hazel gaze. Sam realized that that must have been what was on the angel's mind.

Everything made sense now; Cas was in love with Dean Winchester, but he was afraid what would happen should he confess. "We didn't know what was going to happen, Cas. That's the thing with being a hunter; everything is unexpected. And it's not like Dean is helpless. He's probably been trying to get back to us," Sam said. When Castiel didn't respond, Sam awkwardly pulled him into a hug.

Cas was surprised for a moment, but he hugged Sam back nonetheless. "We'll get him back, Cas. If I know my brother, he'll meet us halfway and will be bitching about what he went through for weeks," Sam said, forcing a chuckle.

Cas smiled a little and pulled away from the taller man. Sam cleared his throat and took a few steps back. "So, you still wanna try that dream thing?" he asked. Castiel looked down at the floor and furrowed his brows in thought. While he hesitated, Sam was thinking about what the other Dean had told him.

Something really bad has happened to someone in my dimension and I need your help.

'Who could he have meant? And why ask me for help when he went to Cas first?'' Sam thought. He had figured out that the other Dean had a brother that was an alternate of himself. Did that mean that the other Dean...had a version of Castiel in his world, too?

Sam remembered the expression of affection and a hint of pride in the alternate Dean's voice when he'd told Sam to speak to Cas for further details. As Sam was contemplating his theory, Castiel looked up with a determined glint in his eyes.

"Yes. Let's do this," he said. Sam's brows flicked up in surprise; he hadn't thought that the angel would actually agree to the dream-walking. To be honest, Sam was wary that it wouldn't work; Dean was in another dimension, after all. Still, he knew that they had to try. Besides, if anyone could get through to Dean, it was Cas.

He nodded and Cas turned on his heel. As he started walking, Sam noticed that the angel was heading towards Dean's room. Sam shook his head and he had to stifle a chuckle of amusement. 'Turns out that I was right, after all, jerk,' he thought, 'Cas does like you better. Better than you might think.'

While Sam and Castiel figured out how to contact Dean within the warmth of the bunker, the other reality's Sam was freezing his ass off. The furnace had broken down about four hours ago and no amount of finagling could fix it. On top of that, the snow had thickened outside and it was beginning to look like a blizzard. The willow trees outside blew harshly in the wind and banged their branches against the windows.

The good thing was that he had figured out another part of the riddle. He hurried up the basement stairs and into the living room. Dean was still hunched over the note, his hands in his hair. It was as though he were staring at the world's most difficult math problem. Sam slid a chair back, startling Dean, and sat down with an excited grin. He rubbed his hands together to warm them then leaned forward.

"So, get this," he began, "the warehouse where the huntress released the virus? There's a train station about eight miles away from it. You remember that part of the riddle? 'Don't dawdle; you've already missed the train'? That must be what the kidnapper meant," he said.

Dean stared at Sam for a few moments then narrowed his eyes in thought. Sam sat back and seemed satisfied with himself. "I don't know, Sam, it seems too easy. Besides, didn't you say that everyone was dead? You think a monster could have taken Cas?" he asked. Sam's face fell; he hadn't thought of that.

"So what do you think it means then, Dean?" he asked. Dean shook his head with a troubled frown. While Sam had been fiddling with the furnace, he had done some thinking. Perhaps the note was meant for him? After all, how could someone from a completely different universe know about the angel Castiel- Dean's Cas?

His head throbbed and he rubbed at his temples. At this point, Dean was sure that he had that stupid riddle seared into his brain. He wanted to crumple up the paper and scream in frustration. It didn't make any damn sense! This was like a bad knock off of Alice in Wonderland!

To make matters worse, Dean could barely keep his eyes open. The dark circles made him look like he'd gotten punched and his brain felt like gelatin. Normally, Dean could still function on two hours of sleep, but he had been through more than even he could handle. Not to mention that he had stayed up with Cas until five in the morning. All he wanted to do was sleep.

But he desperately wanted to figure out the riddle. It was their only way of finding where Cas had been taken. He was just so...tired. Sam, waiting for Dean to answer his question, noticed that the other hunter had zoned out and looked like he was about to keel over at any second. Sam sighed and put a hand on Dean's arm.

He ignored Dean's startled jump and slid the note away with his other hand. "Let me figure out the rest of the riddle. You need to get some sleep," Sam said in concern. Dean rubbed at his eyes with the back of his hand and stifled a yawn. He opened his mouth to protest, but one sharp look from Sam shut him up.

"I can't have you passing out on me when we're this close to figuring this thing out. Get some rest, Dean, you need it," he said. Dean grumbled under his breath but pushed his chair back and stood up. His brows flicked up in surprise as Sam mimicked him. Sam looked at him in amusement.

"Unless you can navigate through the house on your own. I mean, I can stay here if you want," he teased. Dean wasn't sure if it was the familiar glint in Sam's eye or how Sam was acting so much like his Sammy, but he blurted out the first thing that came to mind.

"Bitch,"

"Jerk,"

Sam seemed surprised by his automatic response. Dean tried to swallow the lump rising in his throat and looked away awkwardly. He gestured with his arm for Sam to lead the way. As the taller man moved passed him, Dean could see that Sam was smiling a little. Dean rubbed his eyes again and followed Sam up the stairs.

As the two reached the hallway, Sam found himself looking at his brother's bedroom door. The dark mahoghany wood seemed to mock him. Sadness tugged at his heart and Sam pushed open his own bedroom door. "Here, this is my room. You can sleep in here, if you want to," he said.

Dean heard the depressed note in Sam's voice and tried to catch a glimpse of his expression. "Sam, you okay?" he asked. Abruptly, Sam turned and pulled Dean into a desperate hug. Dean instantly returned the embrace and Sam pressed his forehead against the shorter man's shoulder. They stood in silence, neither moving a muscle. Sam took in a deep breath and let it out slowly.

"I know that I said you'd never be my brother, but I think I was wrong. You being here is...it's sort of given me closure. Even though I said some shitty things before, I'm glad you're here. Thanks, Dean," he said. Dean patted Sam on the back and hugged him tighter. His heart had swelled with emotion and he was trying hard not to cry; Sam had finally accepted him.

"Family doesn't have to be blood. It doesn't matter to me what universe you're from, what dimension we're in, or, hell, even what you look like; I'll always be there to take care of you. You're my little brother, Sammy," Dean said. Sam bit his lip and, for that split second, it felt as though his Dean, his older brother that loved and cared for him, was there once more.

Now, neither would admit that tears had been shed; they had too much pride for that. But tears had fallen on both ends of that brotherly embrace. After they had pulled away and Dean had gone to bed, both men felt a lightness in their chest they hadn't felt in a long time. At some point, the two even dared to think that perhaps everything was going to be alright.

The Winchesters should have known that all good things come to an end. Cas' kidnapper paced restlessly back and forth, her heels making dull clicking noises on the wood floor. Cas lay in the corner, his eyes barely open. "Oh, how long does it take them to figure out a damn riddle? It wasn't that complex," the kidnapper said. She glared over at the motionless Cas and snorted in disgust. "You know, you were way more fun before your hubby died. All that 'broken-heart syndrome' crap is really irritating," she sneered.

Then, without warning, a cat-like grin nearly took over her face and she giggled darkly. "That's it! If they won't come to me, then I'll just have to meet them halfway and give them someone that they will come for," she said. Cas felt a tremor of fear as she turned to look at him with a suggestive look.

Even though the kidnapper looked like Charlie, the once sweet and nerdy girl Cas had known was long gone. "And I know just how I'm going to do it, too," she said. As Cas' kidnapper approached him, he did the only thing his body would allow him to; he screamed.

She clicked her tongue disapprovingly at him and sent a sharp kick against his ribs. Cas instantly quieted, a trickle of blood oozing from the corner of his mouth. The image of his Dean blurred and was slowly fading away. He wanted to cling to it, but he just didn't have the strength.

"Come along, Cassy. We've got a phone call to make."

A/N: I'm so sorry for the wait. I was going to have this chapter up sooner, but my laptop decided to freeze and I hadn't save what I'd written. I had to start all over. Forgive me and thank you so much for the reviews!