This started off as a fill for someone's request, but it ended up going in a completely different direction.
Damaged Goods
Castiel was nearly human. There was hardly a drop of Angel left in him. He hated it. He hated feeling weak and powerless and useless to the fight. He was nothing. He hardly understood how humans could feel like this every day of their lives. But he knew. He knew it was because they didn't know any different. But to go from something so powerful, to nothing. It killed him.
Castiel liked humans. He did. Some he liked more than others, of course, and there were some humans he loved. But to walk among humans, and to actually be one were two very different things.
"I hate this," he said, as he and Dean packed the car.
"I know, I hate it too," Dean agreed.
"No, I mean… this," he indicated to his human body. "Being human. I don't know how you do it. I envy your ability to cope with such weakness."
"Wake up in the morning, kill a few monsters, drink until you pass out. That's how I do it. Nothing to be envious of."
"You're so strong, Dean," Cas said, shaking his head. "And I am useless."
"No, you're not," Dean replied.
"I am," Cas said. "I know nothing of being human. Just walking from one place to the next requires so much effort. Breathing. Needing to eat. I no longer have the powers I once relied on, and I cannot manage a gun. I am useless to you. I am a liability. You would be better off if I just left."
Dean punched him, hard.
"Don't you dare," he snarled. Castiel stared at him in shock. Blood began to ooze from his nose and Dean's features softened. He hurriedly reached for a clean rag in the trunk of the impala and held it to Cas' nose gently. "Sorry," he said. "I didn't mean to hit you that hard." Which is kind of a lie, because yeah he did, but he also didn't want to hurt Cas. "Sorry," he said again.
"It is okay," Cas said. "Just another reminder that I'm not all powerful."
Dean sighed. "You're not the only one who's got issues," he said. "Look at me, I'm the poster boy for just how screwed up a person can get."
"I don't think you're screwed up, Dean," Cas said.
Dean made a strange noise. "Are you kidding me? I know my dependency on Sam is unhealthy. It's got me killed more than a few times. I went to Hell because of it. And I hardly lasted 30 years before they broke me. To top it all off, I just punched my best friend in the face. I'm as damaged as they come."
"At least you have the comfort of knowing that you are what you have always been," Castiel replied. Dean disagrees, because sometimes he felt like he didn't come back from Hell the same as he was before, but he didn't say this. He kept the thought to himself as he took Cas' hand in his own.
"It doesn't matter," he said. "Human, angel. It doesn't matter. You're still you. And you'll learn how to be a human." Or we'll die tomorrow and it won't matter anyway.
"I don't want to learn," Cas said. "I don't want to be human."
"Yeah, well, I don't want to be this good looking and athletic. We've all got our cross to bear." His words bring a small smiled to Castiel's lips. Mission accomplished. "Come on," Dean said, taking Cas around the shoulders and pulling him towards the hood of the car. "Let me show you something humans do. It's dumb, and it's pointless, and oh so human. But it's nice." He handed him a beer and the two of them climb onto the Impala. They stare up at the night sky, name stars and constellations.
If this was to be their last night on earth, at least it was a good one.