This was conceived after Abbadon died, but before The Episode Which Makes Me Want To Step On Eyeballs. Spoilers for the latter half of S9.
This is my headcanon about the blade, and on its relationship to Dean. Kind of a character study, and yes, that blade is a character. CW for addiction-y behaviour and blood. Not a lot, but some.
He's holding the blade, and it tells him, I am Abel.
Dean thinks that makes sense. Cain became what he became to protect his kid brother; it makes sense that Lucifer would make him keep a memento, something to remind him of why he gave himself up.
He's just thankful that he's not carrying Sam's jaw around.
(He likes it in Sam's head. He likes Sam breathing.)
But Abel makes everything so easy. It's like Purgatory all over again, once he got good at it. It was easy, pure: you kill the thing that wants to hurt the people you protect, you spit its' blood off of your teeth - it always gets in your teeth, how does it get in your teeth? - you move on.
But it wasn't so easy.
Because he needed it, needed to keep killing, needed the blood on his teeth and in his hair and in his nailbeds, needed the red dripping and drying on his skin. It kept him sane, kept the itch from tearing off his skin.
He had killed twice with the blade, and each time, he'd felt nothing but calm for days. He hadn't had a single nightmare, his mood was more even, he was better around people. Killing made him feel more human.
And Abel encourages him, every single step of the way. He promises, Next time, you'll feel even better. Next time, you won't spit the blood out. Next time, you'll hug Sammy, and he'll hug you back. Next time, you'll be brave and fast and clever.
Next time, he drops Abel's jaw, and picks it up without moving.
Next time, he doesn't feel human after.
Everything is raw and shiny and buzzing, and he's angry and ruthless and he wants the knife, but they take it from him, and sometimes, Abel whispers, Pick me up and take them down. They want to make you stop. They don't want you.
Dean doesn't know what scares him more; the blade telling him to kill Sammy, or Sammy really hating him, forever.
Crowley is all too eager to let him out, to give Abel back, because the blade is louder than everything else and Dean needs it. He's sick of needing it but he's sicker without it and he needs it, and Crowley understands needing blood.
Everything is a blur, first from using Abel, from fighting and adrenaline, and then because there's a hole in his lungs and he can't breathe but Sammy's got him, and everything will be fine, and he can't breathe, can't breathe, can't -
He wakes up. Abel was crying without him.
Abel needs a big brother to protect him just as much as Dean needs a little brother to protect.
Please review.
