Disclaimer: Eric Kripke is the metaphorical father of Supernatural. Not I.
Warning 1: Thou shall not steal. Plagiarism is a dastardly deed. Thank you.
Warning 2: No beta reader. Apologies for everything wrong, including any uncharacteristic behavior of the Winchester brothers.
Warning 3: Season 9 spoilers
Timeline: Maybe about a couple of minutes after the ending in episode 9x07, "Bad Boys" (I don't really consider this a coda. Only one line/quote from this episode is included, and this line appears at the end of this piece. Events and people in this episode are not mentioned in this work.)
word – thoughts
By Jan J. (P.J.P.), Little Sister's Keepress
He looks over at his brother. Sam's face is shrouded in shadows and ridiculously long hair, but occasionally the passing lights reveal his features.
Dean wants to tell him. Tell Sammy what he did. How he let some entity break into the House of Sam and reside there for the time being. How he invited some stranger to stand between them. But Dean can't.
Dean can't lose his brother. Sam brings out the best in him. Sam is the best of Dean.
He can't let go of Sam. He can never. He needs to protect the one fire—the one light—in his life that burns him but still keeps him alive—still keeps him hopeful.
Dean can't do this alone. He can't hunt—can't function—without the one person he has always protected with his life. Sammy is his life.
So Dean keeps his hold on Sam. He doesn't think about Death, the angels, or God. Dean's hold is stronger. Sam will always say yes to him in the end. Sam must always return to him.
Dean feels. He feels guilt. He knows he's hurting Sammy. Hurting Sam by allowing his little brother to be invaded by the unknown. Hurting Sam because Sam is unaware of the possession.
But Dean doesn't care. Desperation and love—love for this child he always carries in his arms away from the monsters ever since Mom died—build Dean up.
Sam looks back at him. His brown eyes are warm with worry. Dean fears that he sometimes can't tell if he is speaking to Sam or to Zeke. Sometimes Dean wonders if he is really losing Sam right now despite all his efforts to keep his brother.
"Dean, are you all right?" Sam asks.
Dean nods. This is Sam.
"Sammy," he starts. Dean's green eyes emit sadness, but defiance still peeks out.
"Sam, you know that I always do what's best for you, right?" he continues.
"Of course, I know that, Dean." The trust in Sam's eyes haunts him.
"I always have your back, little brother," the elder says, keeping his gaze on Sam.
Sam smiles. "And I have yours." The gaze breaks. Sam peers out the car window.
Dean looks ahead. No matter what it takes, Sammy, I will always have you, he vows.
"Sometimes you got to do what's best for you, even if it's gonna hurt the ones you love."
- Dean Winchester, episode 9x07, "Bad Boys"