Ruby was one of the more unique demons. She still remembered almost as if it were yesterday, what it was like to be human. What it meant to be human, how they thought, how they felt, how they yearned. Yearned for everything – acceptance, purpose, affection. This was the main reason Lucifer chose her to go to the surface yet again to seek out the younger Winchester. A new vessel and a new day. One more try to darken the Winchester's soul and have him deliver what they needed. What Lucifer and Ruby craved. Freedom.

And she thought she could do it. As she studied her new vessel in the mirror, black eyes flickering in and out of focus as she took in the soft curves of her lips, the feel of warm blood flowing through her veins, toned muscles making her stand strong, and all of the cunning of a demon coupled with the mindset of a human, she thought she could deliver to her father. She was invincible.

In the daylight, she could easily see him as a demon should. Sam Winchester was nothing, just some lucky human picked by Azazel to be gifted with the powers of demon blood. But that was just it – he was a human. Weak, lost, confused, unsure, broken. Dependent on her to make him strong, to turn him into something powerful. To help him grow up, grow up and away from his dependence on Dean. She watched him as he struggled to control the power surging inside him, watched as he fell to his knees time and time again, gripping his head in his hands in agony as he wrestled with his own mind. She was a demon, and she knew how easy it could be to crush him if she wished.

But when the lights were off and all there was was the inky darkness of night, she realized time and time again that she didn't want to crush him. She couldn't – the small human bit of her mind that was left was tearing at her resolve. Making the urge to comfort Sam when he fell, to kiss his hair and tell him it would all be okay, overwhelming. And at night, she couldn't hide from these desires. She yearned for him, body crying out for him as she struggling with her own mind. But the night made things so easy – soft, black darkness enveloping them both, wiping out all of the grey areas.

In the night, it was easy. They were simply two mangled souls who needed each other. Needed each other in ways no one could understand – human or demon. And they gave in to the simplicity of it. They couldn't fight what they both so desperately needed. Each other.

"Sam…" His name fell from her lips, and then he was there. His body pressed against her own, hands swiftly making do of the useless clothes. The motions were familiar – it wasn't the first time they did this, not the first time their bodies fit together in the most intimate of ways. And then he was on top of her, kissing her, kissing her with ferocity and want so strong, she could believe for a moment that she was human again. He wanted her, his desire apparent as he pressed between her legs while he undid her jeans. She could lie to herself for a while. Lie that they were just two humans who simply couldn't live without each other.

There were no clothes now, just skin on skin, breathing hot and wet as they kissed. She wrapped her legs around him and pulled him close, desperate to feel his strong body against her own, to feel him around her, inside her, taking her like no one else had ever done.

"Please Sam…"

And then he was moving, making her moan for him, nails digging into his back as he claimed her. Everything was dark and quiet in the small room, the only sounds being their labored breathing and desperate moans, bodies pressed so close together that she could feel his heart thudding against her skin. And she knew he could feel hers, that he could feel how much she needed him. Just lips and tongues and sweat, bodies hot and aching as he thrust and grinded with her, her name passing in hot gasps from his lips.

"Ruby…"

And for a few seconds, it was just them. Ruby and Sam, eyes locked for the briefest of moments as pleasure washed over them. Not a human and a demon, not a hunter and a creation of Lucifer's. Just them. Sam and Ruby. It was as easy as that.

And that's what ripped Ruby apart. Every time they gave in to the yearning and united themselves in the most intimate of ways, Ruby knew that it was wrong. More wrong than Sam realized because Sam didn't know what she was really sent to do. Every time that she felt his warm arm wrap around her, bodies flush against each other as the first rays of morning sun peaked on the horizon, she curled against him and pressed her face to his chest, fighting the tears burning behind her eyes.

Because when the sun came up, she couldn't hide from the truth of what she was. What she was and what she had to do.

She might have been making him strong, but he, unknowingly, was making her weak.