Spoilers for season seven, I guess.
I didn't like how they handled Dean's dream, so I thought I'd write one of my own.
Dean looked down at the woman asleep in his arms and breathed in deeply, remembering every last detail of her perfectly. He had missed her so much, and to have her in his arms once again was pure bliss. He didn't even care that it wasn't real; he knew he was dreaming, but that was enough. It was close enough to reality that he could pretend it was true. Sighing contentedly, he shut his eyes and just enjoyed the moment. This was heaven for him: Lisa asleep in his arms, Sam asleep opposite him, nothing out to get them and knowing that Castiel was watching over them.
"Dean…" Castiel's voice filled Dean's mind, and it scared him. It wasn't normal Castiel; this voice was full of pain and anguish, but Dean didn't know what to do about it. He squeezed his eyes closed, trying to shut out the sound of Castiel hurting so badly and get back to his dream. However, his subconscious had other ideas. When he reopened his eyes, he saw the walls of Lisa's house start to melt, as if they were merely set design. Dean looked frantically around him, trying desperately to make the walls re-form, when he noticed that they were not the only things melting. Sam, the chair he was sitting in, the coffee table, the sofa, even Lisa was running like paint. He jumped up and pulled Lisa with him, trying to reach Sam, but everything was fading too fast, leaving him completely alone in a never-ending white space.
Except he wasn't alone. In Lisa's place now stood Tessa, smiling at him. He freaked out and practically threw her out of his embrace, edging away from her. He tried to regain control of his subconscious and turn her back into Lisa, but she remained the same. He called out after her, asking what was happening, but she simply smiled and tilted her head. Dean couldn't understand; she was normally so kind and helpful, but now it was like she couldn't comprehend what he was saying. Getting frustrated, Dean turned on the spot, looking for a way out, or even just for somebody else to keep him company. When he was finished having his quick fit of panic and anger, he faced Tessa once more.
"Tessa, what do I do?" he asked, almost pleadingly. All she did was raise her arm, motioning in a direction, and wink, before disappearing. Dean let his eyes follow where her arm had been pointing to, but couldn't see anything. But, as his gaze lingered, a corridor formed in front of him. White walls, white floors, white ceiling; all of which seemed to stretch on for eternity. Uncertainly, Dean started to walk down it, looking around for any sign of what to do. He hated this; the uncertainty, the not knowing, the walking without direction.
"Dean…" Castiel's voice echoed throughout the corridor, bring Dean to attention. He ran blindly after the voice, desperately trying to reach the angel. He ran for what seemed like forever, until he came across a sight that nearly made him sick. Castiel was hanging by chains, bleeding, crying out for Dean. Hooks ripped holes in his skin and he kept flinching, as if reacting to being hit. Dean couldn't bear it; seeing Castiel in pain was bad enough, but all of this was forcing memories of Hell to the forefront of his mind. Tears sprung to his eyes and he reached out desperately for Castiel. He wanted nothing more than to free him and embrace him and make him feel safe, but he couldn't.
"Cas? Cas, I'm here, I'm here, you called for me and I'm here," Dean choked out, barely able to speak. When the angel did not react, Dean called out to him again, "Castiel, I'm sorry, but I'm here now, please, Castiel, be okay." When Castiel still didn't reply, Dean decided to take action. He gingerly tried to remove the hooks holding Castiel, but he only winced and tried to shirk away from him, still not acknowledging his existence. Dean couldn't understand; he was trying to help Castiel, not hurt him, but he was acting like he had put the hooks in himself.
"Dean!" Castiel's scream was heart wrenching, and tore at Dean's soul. He reached out his hand again, to touch Castiel, to let him know that he was there, and this time, he turned to face him.
"Cas? Cas, I'm here, and I'm gonna get you out. I'll never abandon you, Cas, just stay with me, please…" Dean's ramblings were cut off by Castiel's eyes widening in terror. Dean span on the spot to see what Castiel was looking at, but there was nothing behind him. Thinking that the angel was hallucinating, Dean put his hand on his shoulder to comfort him, but he flinched and squeezed his eyes shut, as if expecting pain. Then, Dean realised. Castiel was scared of him; thought that he was going to hurt him.
"Dean, please help me!"
"Cas… Cas, I'm here… I can't… I don't under… CASTIEL, PLEASE!" Dean's exclamation only scared Castiel further, and it pained Dean to see those big blue eyes so full of fear, especially because of him.
"He doesn't recognise you?" a voice, behind Dean, asked. "Is that really such a shock? Do you even recognise yourself?"
Dean turned around to find Sam standing behind him. Not registering what had been said, he ran to embrace his brother, only to have Sam push out his arms so that Dean was forced to stand back. It felt like a punch in the stomach, although no physical contact was made. Dean's face dropped; not only was Castiel afraid of him, but now Sam didn't want to be near him? The hurt must have been plastered all over his face, because Sam laughed and took another step back, mocking him.
"Does baby want a hug?" he asked patronisingly, "is baby going to cry? Does baby need a kiss and reassurance? I think the things we really should be asking are: is baby really going to rely on his brother all his life? Is baby really going to destroy himself and pull his brother down with him? Is baby going to ignore his own brother's pleas for help and let him fall apart?" The words cut through Dean like a knife, and he had to hold back tears. Sam noticed this and smirked, sending shivers down Dean spine. Sam's eyes were full of anger and hatred, and it didn't suit him. His eyes were meant to be full of laughter, of happiness, but something had changed him. Dean realised, suddenly, why Castiel had flinched, why Sam hated him; he was a monster. He was the one who had turned Castiel away when he had needed him most, he was the one who had ignored Sam in his time of need, he was the one who was so detached from reality that he couldn't notice the people around him in pain.
"Sam, I…"
"No, Dean; for once, you're going to listen. You spend so long lecturing your brother, but when do you ever take the time to actually listen to him? He's told you so much over the past few weeks, but you've ignored it and carried on as if nothing is even wrong. He's suffering in here, even more now, and you've let it slide right by, and now you've let this happen…"
If it were possible, Castiel's eyes grew even wider as Sam spoke. At first, Dean didn't understand, but then he realised that Sam had been overtaken by Lucifer. Had Sam been trying to tell him something lately? He'd said that he was seeing Lucifer, but Dean had brushed it off as if it were nothing. He'd calmed him down that one time he was shooting into nothing, but what else had he really done? Left him to deal with it alone, and now look where they were.
"Castiel? Ever so sorry, brother…" Sam… No, Lucifer clicked his fingers, and Cas was no more. Dean ran to protect his angel from harm, but he was too late. As he approached Castiel, he only got further away. The angel gave him one last look of hurt and suffering, before liquidising. The water surrounded Dean, growing higher and higher, until it was nearly up to his chest. He tried to swim to stay afloat, but the water was rising too fast for him, and eventually he was completely enveloped it. All the while, Lucifer was standing, unaffected by the water, watching Dean struggle. He laughed humourlessly and mocked Dean's attempt to regain breath, before clicking his fingers and appearing right in front of Dean's face.
"Sam…" Dean attempted to say, to no avail. All he could do was watch as Lucifer toyed with him. He drained the water just enough to give Dean breath, before making it rise once more, suffocating him.
"No, Dean, you are not going to plead with Sam. You are not going to plead with me." As the last words were spoken, Lucifer reversed Sam's age, turning him back to his fourteen year old self. "Remember me?" he asked, "I was that boy that looked up to you, that adored you, that worshipped the very ground you walked on. I was that boy that you pushed away when I needed you, that you chose Dad over, that you let go. But then I was free, Dean, I was away from everything. I was away from Dad and, more importantly, away from you. I was happy, but then you came crawling back to me and forced me back into this life. Everything that's happened to this little boy is on you, Dean, and there's nothing that's ever going to change that. You know, and I know it, too. I hate you Dean, I hate you more than anybody." Lucifer clicked his fingers once again, and all the water was drained. Dean gasped at the air, thankful for its presence. He knew that Sam wasn't saying this, that Lucifer was, but it still hurt nonetheless. He knew, deep down, that all of it was true. He had hurt Sam, he had pushed him away, he had been the reason he'd come back and gotten hurt.
"I'm so sorry…"
"And what about Castiel? He trusted you. He loved you like I did, and you let him down too…"
"Stop, please, stop…" Dean begged, wanting to wake up.
"Fine, I'll stop. But, Dean, only because the worst punishment is that you already know all this; me telling you isn't the worst thing. If I stop now, it leaves you to think on everything else that you've done, and all the people you've hurt…" And, with that, Lucifer was gone, and Dean was alone again; alone to reflect on everything.
The image of Castiel screaming wouldn't leave his memory. Was that what he had felt when the Leviathan had taken over? Had he been screaming in pain, calling for Dean to save him? He had come to Dean for help, and Dean had sentenced him to death. He knew that making him give back the souls had been the right thing to do, but it had killed his best friend. His face as he had asked for forgiveness flashed into Dean's mind, followed quickly by many more: Castiel when he first met him, pulling the sword out of his own chest and sighing; Castiel saving him, over and over again; Castiel telling Dean he would rebel; Castiel's dying face; Castiel when he was no longer Castiel, when he was Leviathan. The images played over in Dean's mind in quick succession, until he was forced to squeeze his eyes shut and scream to shut them out. But they wouldn't leave, and they were soon joined by childhood memories with Sammy.
As Dean screamed and screamed and screamed, the walls around him started to crumble. "I feel… Regret." One brick down. "Dean!" And another. "Jerk." And another. Words and images swam around his head as the walls fell, and Dean was forced into the foetal position. Brick upon brick smashed into him, causing him more pain than he'd ever felt before. He heard a footstep and opened his eyes to reveal Lucifer standing over him, smirking.
"I told you leaving you alone with your own thoughts would be the best punishment…" Lucifer lifted Sam's foot and slammed it down into Dean's skull, but before he could make contact, Dean's eyes shot open and he sat bolt upright in bed, breathing heavily. He looked at the bed next to him and, when he saw it was empty, panicked. His heart was beating too fast to be healthy, but nothing he did would calm him down. He rubbed his eyes, knowing that he wouldn't go back to sleep, reached for a bottle of whiskey, and poured himself a glass.