Sam rushed to Dean's side and caught him right before his knees hit the ground.

"Dean? Oh God." Dean was scarily heavy. Sam felt his panic build in his guts.

"Dean, please. I'm sorry… I should have never let you leave… Oh God…"

Sam looked at his hands terrified. There was blood coming out of Dean's nose. He tried to get a hold of Dean's shirt.

"Come on, you can't leave me Dean… not now… not when I just realized how much I need you… Dean?"

He called his brother's name. Dean was completely out now. Sam almost stopped breathing for a few seconds before he realized that Dean still had a pulse and he was breathing. Ok. Maybe it wasn't that bad. Sam had to get it together somehow. He knew Cas wasn't gonna show. He was looking for Gadreel and had decided it was too risky to be near Sam when he was looking for the angel.

He struggled for a few seconds before he got a hold of the situation and had Dean hanging from his shoulder. It only hit him then how weak and thin his brother had gotten.

"I'm sorry Dean…" he whispered at the rush of guilt in his heart. He was an idiot for letting Dean go away like that. Wandering around so hurt and feeling so low. Sam even had Cas there with him, Dean's only friend. He couldn't imagine what Dean had been through and by the looks of it, it had been bad.

He got Dean to the car and settled him down on the shotgun. He was in the car in a blink and was driving towards the bunker. He needed to know what was happening to his brother.

"Oh God…" He said as he thought of the possibility of Dean trying for the trials again. He brushed his hair back on his head and pushed at the tears.

Why hadn't he thought about this? A hopeless Dean was the worst Dean ever. He got suicidal and reckless and he tried to hurt himself.

He didn't even think when he took Dean to his own room, placing his brother on his bed. He was gonna back away and run to the library when a hand, Dean's hand, fisted his shirt and kept him in place.

"Sammy… I'm so sorry… I'm sorry Sammy… I didn't mean for this to happen… he didn't tell me… Sammy I'm so sorry…"

Sam couldn't really understand the words, all he could care about was that Dean was crying. Dean, his big brother, his hero, the guy he always wanted to be, was crying and he looked so little like that. It wasn't his prideful tears, or his hurt silent crying. Dean was sobbing and he sounded like he was feverish.

Sam felt sick.

Only then he noticed the new red mark on Dean's arm. It was familiar to him and Sam knew it wasn't a tattoo. It felt alive, like it had a mind of its own.

"Oh God, Dean… what have you done?"

He took a picture of Dean's hand when his brother knocked unconscious again and ran to his laptop. He needed to know exactly how deep in shit they were.

He cursed himself inwardly for letting Dean go away on his own. They both knew how they got when apart from each other.

Sam would become this obsessive bastard running to catch a glimpse of the normal life.

Dean would turn to a killing machine and closed his heart.

Sam's knees almost gave in when he read the words on screen. Dean had taken Caine's mark. He was now exactly a killing machine.

Sam understood now. The weakness, the blood, the unconsciousness.

Dean was fighting this thing possessing him. And he was wrecking his body. The muscular guy who had left Sam 3 weeks ago was now only a pile of skeleton and skin.

Sam felt sick.

How had this happened? It said there that the mark would only shift if both parties wanted it to. Why had Dean accepted this? He was smarter than that. He must have known it would lead to his death or the whole planet's.

Abaddon. Dean had killed her about two weeks ago. He had called Cas to give the news and he never told him how.

Now Sam knew how and he knew Dean well enough to know Dean had hoped that this whole thing was gonna be the end for him.

He felt like choking on air. He needed Dean. He loved Dean. He loved his brother more than anything in the world and he hated himself for ever forgetting that. He hated himself for pushing Dean away.

He heard Dean's voice calling for him and he ran to his room, kneeling by his side.

"Dean, I'm here. I'm here brother." He felt his tears rolling down his face.

Dean clenched his shirt again.

"Sammy… is this really you? No… it can't be… I'm just imagining this… what a pathetic looser you are Dean… your brother hates you, doesn't want to be near you and you still ache for him..."

What hurt Sam more than Dean's words were the far look in his eyes. Dean's eyes had lost their glow a long time ago but they still had had life in them before he left Sam. Now it was empty. Even the always too green shade was very close to gray now.

"Dean I'm real. I'm here. You're here. You're home Dean. You're with me."

Sam's tears fell on Dean's face and Dean looked at him like he could see him now.

"Sammy, my baby brother, you look like you're getting better… Cas is healing you right? tell him I'm gonna climb out of hell and kick his ass if he doesn't." Dean chuckled a little.

"Shut up dean. You're not gonna die. Not today. I'm not gonna let you. You can't die Dean."

Dean just gave him a sad smile. Oh God, Sam felt his heart shatter. What he wouldn't give right now to see Dean's real smile. To see his brother smirk again.

"You can't stop it Sammy. This is for the best… you know I'm poison... I can't put any more people in danger Sam… I can't put you in danger… I needed to take care of you, to make sure you were ok, and you are. I killed Abaddon and Gadreel and Metotrone too. Crowley made a deal, he won't hurt you or Cas. Cas is gonna take care of you… he's gonna take care of my pain in the ass little brother…" Sam hated how Dean's eye's were losing focus again.

"Dean stop. You're no poison… you're a hero Dean. You're MY hero. Always have been."

"Doesn't matter Sammy… I'm cursed. Everyone around me dies. And you don't have to pretend anymore… I know you lost what we had a long time ago…"

"Dean…" Sam tried to protest. He needed to reason Dean that he cared. But his actions were all against his words and he knew he had made Dean feel unwanted and unimportant.

"Sammy… you don't owe me anything. I'm sorry I brought you back so many times… you know how to live without me but I don't… Sam I can't live without you… I just can't… I had promised you I would always save you if it was the last thing I did. I wouldn't break it…"

Dean trailed off and Sam made an attempt to dry his tears, clearly failing since he was soaking Dean with his own tears.

"Dean…" Sam felt sick to his stomach. He wanted to make things ok. He needed to comfort Dean. He needed to save Dean.

"Dean you can't die. Not when there's too much stuff between us… Dean I can't live like this… I can't let you go like this… Oh God…"

Dean was bleeding again and now his whole buddy was shaking and moving uncontrollably. Sam knew better than to try anything. Deep down, he knew he couldn't save Dean.

He never could.

Not the 103 times Gabriel had killed him

Not when Lilith had sent his dogs to tear him apart.

Not when he had gone to purgatory.

And not now.

Dean's body stopped moving and he fell weightlessly on Sam's bed. He looked more peaceful now.

"Hey Sammy…" Sam was afraid to look into those eyes and see anything but his big brother.

"Look at me man… I wanna see your face one more time…"

He sounded too peaceful for a dying man and Sam hated how hope started in his heart. Because he knew Dean was dying.

He looked at Dean. He was smiling. It was genuine and Sam found himself smiling.

"You know, when I was younger, there were so many times I just wanted to end my life… it was too hard Sammy… especially when we were kids… I hated my life and I hated dad… but you were always this shining thing in my life and I always held on because of you. I knew it was my job to make sure you wouldn't go through the same stuff… and when you went for college, I was hurt because you left me but I was more proud cause my baby brother was gonna have a good life." Dean's smile faded away.

"I'm sorry Sam… I'm sorry for always ruining your life… I should have never come for you in Stanford…"

"Shshsh Dean… it's ok… none of this is your fault…"

Dean wasn't hearing him anymore. Sam could tell. His body was becoming lighter by second.

"I'm sorry Sam…"

And then Dean was gone. Sam just knew it. He could feel with his whole body how the world suddenly was missing something. Something big.

He let the sobbing take control and held Dean's lifeless body close to his chest, crying hard.

He remembered Dean leaving a normal life to be with him in high school. He remembered Dean helping him fill the college applications. He remembered Dean selling his soul for him. He remembered Dean going to hell for him. Dean fighting his destiny for him. Dean forgiving him. Again and again. Dean dying to talk to death, to get his soul back. Dean leaving Lisa and Ben for him. Dean always putting him first.

How was he supposed to live without his brother now? How was he supposed to let Dean go?

"I'm gonna get you back Dean…" he whispered. He didn't know how but he knew he would get Dean back.