Sam listened to the blues as it lilted across his worn soul. The sigils painted into his ribs burned; Lucifer was near. Lucifer would find him and take him as his vessel, Sam was sure of it now. He finally understood the tools his father had armed him with. No-one had known who Sam Winchester would become. The Angels thought they knew in same way they thought they could win this war. The demons believed they knew, believed in a legend that was lost for eons. Even Sam hadn't known, had believed in a normalcy that was never his to begin with. But John Winchester had known, had faith in his son's strength to beat the unbeatable.
So as Lucifer walked into the bar and straight up to him, Sam straightened up and said one soft word; "yes."
The memories flowed through his veins, those extra training sessions that not even Dean had known about. Like finding a long discarded toy, Sam remembered what he had forgotten with wry fondness. The resentment he had felt back then turning to measured hope as Lucifer pooled into his meat-suit.
Sam hummed silently, waiting for Lucifer to finish. The force wanted to crush him, he gasped suddenly unsure he could do this. Remember – a silent whisper in his mind. Sam began to fight the urge to resist, though it seemed an impossible feat. His mind and body and soul screeched at him in synchronicity to not allow this painful evil thing- to fight it. But he pushed down the instinct to resist the crushing weight. And for a moment let the power wash over him. Then he managed to stop resisting for a little longer, and the power burned through his entire being, but he kept his soul still, unresisting with the stubbornness of a Winchester.
The pain was unbearable and unrelenting, Hell's playground unleashed into a fragile mortal frame. And Sam remembered. He stayed pliant to the pain. Eternities went by, and Sam's hope dwindled, his mind swayed, and his soul emptied. But Sam still remembered and so he remained as a marble statue in a sea of remnant dust.
Sam felt horror and revulsion as the devil nonchalantly whispered his plans to him. But still Sam stayed unresisting. Maybe Lucifer was just taunting him, but maybe Lucifer was scared, because he was close now, so close. He could win this, he would win this. Lucifer lashed out at him with tendrils that cut so far Sam had hardly known that those depths existed. And Sam almost pushed back, almost pushed away the power he had waited so long for. Except remember shouted softly, stopped him. Time had become meaningless lifetimes ago, but now it was all that mattered. Just a few more minutes or seconds even and he would defeat them all. The power would wash into him, all he had to do was let it.
Lucifer screamed in fury at the idea of leaving one cage for another and then calmly whispered promises of punishment. Sam stayed still. Lucifer plagued him with images of Deans stay in Hell. Sam let out a grimace and remembered as the first sparks of Lucifer's Grace flowed into him, silencing the Devil for good.
Remember, watch out for your brother; watch out for Dean.