Castiel opened his eyes. Complete and utter nothingness greeted him. He was in the Empty, once again. But why… why was he awake? He made peace, he made himself feel that moment of happiness when he told Dean he loved him, without any restraints, without any doubts. He did something for himself, but at the same time sacrificed all he was for Dean.
"Hey!" — he yelled. — "Anyone there? Empty? Billie?"
All he could hear was his voice. No answer followed. So, he decided to just walk… somewhere. As he was walking, he couldn't do anything except thinking, and after a while his thoughts drifted away to a familiar topic. He thought about Dean. Was he alive? Castiel stopped lying to himself after that moment when the other angels told him he had to kill Dean to prove that he was loyal. During his past life he didn't really think about humans as something other than simply the work of art created by his Father. God was the most important being in the universe, and Castiel just did like he was told, believing that he was doing God's work, following His orders. He felt something when he filled the human vessel for the first time in ages, but he had a job to do at the time, so he flew to the barn where the chosen one was awaiting him. He had to protect the seals, guiding this tiny human, avert the rising of Lucifer, so he never really had time to stop and think. But then, in the Green Room, after Dean called him soulless and told him that he was already dead, Castiel felt something. He couldn't understand what it was at that time, but it felt so strong, so… right, that he suddenly felt his purpose, his goal shifting. Castiel, invisible to Dean, looked at the human in front of him and that human stopped looking tiny. He disobeyed, he rebelled, and he felt… different. Past Castiel wouldn't even think much about an opinion of a human before, but this new Castiel — he started caring. And so, he fell. Years went by, and the human beside him looked bigger and bigger, until he became Castiel's whole world. Before being handed the knife to kill Dean, Castiel had doubts about his feelings. He thought that he was becoming more human because of being close to people. He thought that what he was feeling was human kind of friendship, camaraderie. Human feelings were much stronger after all. Dean was his brother in arms, they fought together, they've been through much together. But weren't the angels his brothers, too? Being forced to choose was horrible, but at that moment Castiel realized that he wasn't choosing anymore. He had already chosen, long ago. Metatron knew it, too, so he used it as a weapon to hurt him. After hearing about Dean's death Castiel was devastated and nearly killed Metatron. The only thing that stopped him was knowing that Dean must be somewhere in Heaven, and that they could meet. Castiel wanted to confess, to tell Dean everything, but no matter how thoroughly he searched, Dean wasn't there. When Sam told him about the note, he was relieved, but then scared. His vessel was deteriorating, and he was running on fumes with his stolen grace, so he couldn't really help. Hearing about Dean turning into a demon was so painful — he thought that he was dying. It felt like falling deeper than the deepest depths of hell. Castiel experienced this feeling once more, when he realized what was wrong with Dean, and learned about his mark.
"I'll have to watch you murder the world" — he told Dean, because there was no way he would try and kill Dean, even if he murdered everyone in existence. Even lying on the floor, covered in blood, Castiel never thought about himself, he was only scared for Dean. He didn't want to remember him becoming a pawn of leviathan and devastating heaven, but he had to admit that even then he didn't kill Dean, even though he wasn't really himself and had the power to reduce any living being to atoms. He chose to run instead.
Castiel wanted to tell Dean, all this time, but for some reason this was harder than fighting any battle. So, he kept looking at him, foolishly trying to make him feel it just by looking into his eyes. He almost confessed during that ride with Dean in the impala before letting Dean go basically kill himself turning himself into a Darkness-killing bomb. But then Dean told him he was like a brother to him. Family. Like Sam. So Castiel kept silent. He wanted to die with Dean, stand with him until the last moment, but Dean denied it, so he had to step away. When Dean disappeared, it felt like the world ended, but there was Sam, and his promise to keep him safe. The ride back to the bunker after being blasted away felt like years. Then he saw Dean again, but he was with Mary, so Castiel kept silent again.
When he thought that he was going to die because of the poison from the Lance of Michael, he let himself speak the truth just one time.
"I love you," — he said, but Dean said nothing, so he decided to add "All of you." To not make Dean carry this burden by himself.
When Castiel stepped out of the portal after leaving Lucifer behind, he was so happy to see Dean alive, but then he found himself in the Empty. Without Dean. And the Empty looked deep into his fears and told him what he already knew — Dean would never love him in a way Castiel loved Dean. But still, he fought to get back to Dean, selfishly this time, just because of the very human desire to see the person he loved. He wanted to tell Dean the moment he saw him getting out of the impala near that payphone. But Dean hugged him like he would hug his brother and quickly stepped away. Then Castiel met Jack. Dean taught Castiel to love, and the not-so-angel-anymore became a father. He was happy just to be near Dean, but the peace and quiet didn't last long, so he had to save both Dean and Jack, Dean from Michael, and Jack from falling apart, and then — from Lucifer. Then there were parallel world problems, and then God, and Castiel couldn't stop and think again — he had to help Dean, and Sam, and Jack. The decision to make the deal with the Empty was easy for him: Castiel thought that he tricked the cosmic entity. He would only be happy if Dean accepted his feelings, but that would never happen. There was a zero chance of failure. He was thinking about the way to let Dean know though because, albeit a dozen of years was a very short time for the angel who lived for millennia, it was becoming hard to keep it in himself. But then an unspeakable happened. Jack killed Mary. Looking Dean in the eyes… Feeling his anger… It was worse than all the fires of hell he had to endure to raise the righteous man from perdition. And then Dean told him that Castiel didn't exist for him anymore, so he walked out of the bunker. He felt like he was walking on molten lava or knives, and every step he took felt more and more painful. Castiel wanted Dean to call out to him, but it didn't happen. So, he went away, but being without Dean was so unbearable that he had to return. At that point Castiel didn't have any doubts about God. God wanted to kill Jack, and he wanted it done by Dean or Sam. Everyone knew that Dean would be the one to land the blow. Castiel wanted to hide Jack, to run, because he couldn't bear the thought about people, or beings, he loved killing each other. Then God killed Jack, he was gone, and Castiel was frozen… But Dean was still at his side, still alive, so with enormous effort he grabbed Jack's body that felt heavier than anything he ever lifted, and ran, not wanting to see another loved one dying.
Killing Belphegor hurt him so much, he felt like he was the one burning in his vessel, no, his body — at that point he was more human than angel. But he still thought about Dean, felt the need to protect him at all cost, so he kept going, despite all the self-hatred, despite all the pain. Seeing God as the new enemy didn't make Castiel feel any doubts, he would kill anyone, deal with anyone who dared to threaten Dean. He stood with Dean even if it meant going against his Father who gave him life and created the humanity.
When Castiel was going to try to kill Death, at Dean's side, again, he never gave it much thought, he was ready to die any day if he would be dying for Dean. He was ready to fight until the last breath, but in the end, it turned out to be that in order to at least help Dean survive he had to give up instead. When he realized what he had to do this last, this final time, Castiel ruined all the walls inside himself to try and feel true happiness for at least a second. A second that would give Dean time. When he started telling Dean, he suddenly felt that he was lifting a burden, that he was becoming lighter and lighter. When he finally said the three words he wanted to say for years and prepared to die, throwing Dean out of the Empty's way, Castiel smiled. He was at peace. He was complete.
But after waking up in the Empty he realized that it was a lie. He wasn't near Dean, once again. He didn't know if Dean survived, and it felt like a red-hot nail hammered right in the middle of his chest.
Castiel's thoughts were interrupted by a human hand appearing out of nothing. He stopped with a jerk and stared at the blinking extremity. Then he saw a shoulder, and the clothing looked very familiar. In a second Jack completely appeared in front of Castiel, accompanied by… a round piece of space from the bunker?
"Castiel!" — he exclaimed and hugged him, squeezing so hard that it hurt the angel.
"Jack!" — Castiel shouted, — "What happened? Why are you here? Did Chuck kill you? What happened to Dean and Sam?"
Jack looked surprised. He looked at the piece of the map table he brought with him and frowned perplexedly.
"They're physically fine. Dean is crying though, because of you. Sam is drunk. We were… talking, but then I got a strange feeling… And then I just… appeared here. What are all those beings?" — he asked.
Castiel looked around, but there was no one — the Empty was, well, as empty as ever.
"What do you mean? Where?" — he asked.
"Below us, I can feel them" — Jack said, opening his eyes wide. — "I feel power over them, like I can… Wake them up. Should I?"
"Wait… What happened when Billie teleported you here?" — Castiel was as surprised as Jack, but an idea crossed his mind…
"I exploded, and the Shadow took my face in its hands. I felt that something… was changing. Like that time when I got my soul back — it was like there was one me, and then there was another me. I thought I was hearing something loud, but then Billie teleported me back." — Jack put a finger to his lip like a child would do when thinking.
"Sorry, I don't know if it makes sense." — he added.
Then Jack crouched down and pulled something from the empty. It was a scythe. Billie's scythe, in fact. Castiel and Jack looked at it and then looked at each other with wide eyes.