Castiel was not all fluffy wings and halos anymore. He needed sleep and food and drink now. His body ached constantly, his skin wrinkled, his hair grayed but Death refused to save him.
The devil moved through Castiel's mind now.
Learning
He learned to make Castiel hurt and to make him ignore food and sleep. He learned to make Castiel have nightmares and how to make dreams turn into nightmares. He learned to make his rat more human and less at the same time.
"Go on, Castiel, chew off your hands. You can do it." Lucifer hissed.
"Please…" Castiel croaked his breath ragged and painful in his chest.
"Please!" Lucifer mocked with a screeching laugh. "Please, Lucifer!" He held his stomach and let out another screech of laughter. Then his hands dropped and his face went blank and still angry. "Please, Michael, Gabriel, Raphael, Joshua, Balthazar. Please, Castiel." He circled like a vulture or a snake, his eyes boring into Castiel.
"Lucifer…"
"You know humans have the jaw strength to bite off their fingers like baby carrots?" He leaned his face close to Castiel's and let his rotting breath fill his brother's nostrils. Castiel tried to pull away but Lucifer placed his hand on his cheek. "But you're not human, are you Castiel? No, you are stronger and somehow… weaker. I bet you could do it. Are you going to try?"
Castiel passed out then and Lucifer let him sleep, planning to wake him with an image of Dean's death in a few minutes.
Lucifer sat down and watched his brother sleep and remembered.
He remembered Castiel as a very small angel who had trouble learning to fly, how ironic that he would one day fall.
He remembered watching him with the others, the way Gabriel tormented him, Raphael ignored him, Balthazar played with him, and Michael taught him. He had had very little interaction with Castiel when he was small. Lucifer had spent his time doting on Michael and getting pushed away every now and then only to run back. But he remembered what Castiel had been like.
He remembered standing on a beach, watching a little gray fish hauling itself over the sand and hearing Michael say to him "don't step on that fish, Castiel, big plans for that fish." And he remembered the overwhelming urge to squash the fish beneath his feet and fling it back into the sea to teach all the other fish what happened when they reached the land.
He didn't remember Castiel on the day of the fall. Had he cried? Stood quiet? Begged for mercy on his brothers and sisters? Lucifer could not remember. He remembered some like Hael, patron angel of kindness, who had not defended their actions but had fallen to his knees before Michael and his court and begged for forgiveness. He remembered how Hael and the others had been swept aside and removed from the court, screaming for Father's justice.
He remembered Omias, who cursed his name only to fall a thousand years later. He remembered many of his siblings and the way they protected him or cursed him or, like Michael, followed their father blindly and dutifully.
Castiel began to turn his head back and forth with increasing violence. His back arched and he threw himself back and forth as though being electrocuted. Lucifer smiled viciously as Castiel was woken by his own scream.
"Poor little Dean." Lucifer mused. "So small, so weak and he thinks himself a hero."
"Dean isn't…hero…doesn't…think."
"Do you know what hell is like, Castiel? No, I suppose you don't. Let me tell you." Lucifer stood and walked to Castiel's beside again. "It burns, Castiel. The fires seem to know exactly what hurts you most. It's not just physical, it's psychological. It burns you all the way through until you hurt so much that you can't even feel."
"I'm…sorry…no choice."
"But isn't that what you fought so hard for, Castiel? You said it yourself. You tore up the ending and the rules of the great story and you left nothing but freedom and choice. Is free will only for them?" Castiel's eyes were broken and edged with tears. "It was, wasn't it? You fought for free will that you knew you could never have. Don't tell me why. I already know. For the love of man, but not just any man and certainly not all men, just one. Just Dean Winchester. Isn't that right?" He hissed his serpentine tongue sharp and his words poisonous.
"No…" Castiel whispered, he started to pass out again but Lucifer shook him.
"No, that's far too easy, little brother. I'll break you first and then I'll break Dean and then I'll return to Samuel. You'll be to dead to stop me, little brother. But for now, we can be together."
Lucifer smiled slyly and let Castiel fall asleep to a lullaby composed of screams.