Life had been more than busy for the Winchesters lately. There were the cases they were being given by the British Men of Letters, constantly worrying about either Castiel or Mary and wondering if they were okay, and then there was the problem of the nephilim. Seeing as their recent plan to help Kelly had completely fallen apart thanks to Dagon finding them and taking Kelly away again, Sam was doing his best to think of something new. But there was nothing. She'd seemed pretty far along in her pregnancy last time he'd seen her, which had been surprising. Then again, it wasn't like the baby was completely human. So now he was in the library attempting to figure out when the nephilim would be born.

Dean had gone to bed already, but Sam hadn't even bothered with that. Sleeping wasn't something he was good at these days. Sometimes he'd attempt to fall asleep, but terrible memories of being Toni's captive kept him awake. And there were other memories, older ones that seeing Lucifer a few months back had brought up. Sometimes he did fall into the deep embrace that was supposed to be comforting, but nightmares attacked his unconscious mind, and he'd always wake from them with a start, his sheets a mess, and his body covered in cold sweat. Getting enough sleep was a battle for Sam, and tonight he didn't have the strength to put himself through that. So he stayed up, deciding that he could at least use his time to figure out when Kelly would give birth.

The work wasn't easy. There were books to pore through, notes to take, and equations to create. Sometimes the work grew tedious and boring, and during those times Sam caught himself yawning.

Maybe I should go to bed, he thought.

He quickly brushed that aside, telling himself that the work he was doing was too important to be interrupted with sleep. That was only part of the reason; battling to even get a few minutes of rest wasn't something he was willing to do. It was just too… hard. Sam felt weak thinking like that, so he quickly reapplied himself to his work.

Though the Men of Letters had information about many different creatures all he could find about nephilims was theoretical. None of them had ever come in contact with them, and others didn't even truly believe they existed or could exist. One book he found discussed the impossibility of nephilim, claiming that angels, being celestial beings, did not contain DNA. The author argued that while the vessels they might possess had DNA that their spirit did not fuse with that. Sam scoffed at that, knowing fully well what it was like to be possessed by an angel, so he put that book aside and picked up another one. The author of this book constantly referred back to the one he had just been reading, making a point in arguing everything that had been said. Given some of the language used this didn't just boil down to a scholarly debate, so Sam also put that book aside, not in the mood for reading about petty disagreements. Though, Sam had to give them a point for knowing that angelic grace partially fused with the vessel and stayed in them past the time they'd been possessed.

That got him thinking about Gadreel. That was one particular angel he didn't care to dwell on given all the negative experiences he'd had with him, but something itched at his brain. He couldn't put his finger on what it was just yet, so he kept on researching nephilim.

It was difficult to find something that went beyond theoretics, but after a lot of digging, Sam found something that might be of help. The book had been buried deep within the library, suggesting that the material it contained wasn't something a lot of the Men of Letters agreed with.

As he sat down with it and started reading he began to have hope that his research that night would get him somewhere. The opening was short, and simply stated that it was going to delve into the actual topic of nephilim, and some facts about them, rather than just wondering if they existed. The book was incredibly helpful, and he even managed to find a chapter about fetal growth rate.

Eagerly, Sam jotted down notes on the table as he read, and his thoughts began to come together.

However, at one point, when he had just started coming up with variables he would need to create an equation, he began to despair. What if all this was for nothing? The book itself discussed the nephilim of angels, not archangels. Then again, Sam had been possessed by both an archangel and an angel, and he guessed that the major difference between them was how much power they wielded.

Against his will his mind began to travel a dark road, remembering what it was like to be possessed by Lucifer. How Lucifer could search through his mind as he liked, taunting and teasing. How he'd lost full control of his body, and could only watch as Lucifer ripped demons to pieces, could only watch as he snapped Bobby's neck, blew up Castiel, and beat Dean senseless. And then… and then he'd gotten control, and he'd thrown the two of them into the Cage.

A shudder ran through him, and the words on the page blurred in his vision. He squeezed his eyes shut, and shook his head slightly, trying to regain his focus. But when he opened his eyes again he wasn't in the library. Everything was pitch black, void of any light. There was a voice whispering to him, and he couldn't make out the words, couldn't even tell whose voice it was.

It grew louder and he began to pick up what it was saying, who was speaking. It was Lucifer. "You can't win, Sam. All this research, all this work, it's pointless. You're going to die. And then you're going to end up back with me."

He appeared before him out of the dark, standing above him, and Sam realized that he was on his knees, his head tilted upwards to meet his gaze red-eyed gaze.

"No, that won't happen," he argued.

"It will. My child is going to be strong, undefeatable, and once they're born nothing can stop them."

Despair washed through Sam and he lowered his head. A hand brushed against his cheek, and he tried to move away from it, but he was frozen in place. Fear made goosebumps rise up along his arms, and sweat began to bead on his forehead.

Lucifer crouched down beside him, one arm wrapping tightly around his shoulders, and he breathed in his ear, "Sam, I can't wait to see you again."

Sam came to with a start, and realized that he had been dreaming. He rubbed at his tired eyes, but now he was more determined than ever to get back to work. Maybe it was all pointless, maybe everyone was going to die, but he wouldn't let himself fall asleep again. Not yet. The nightmares were unwelcome. So he tried to work without thinking about the why. It greatly disturbed him that Lucifer had used Kelly's body just to conceive a child. He more than most knew that Lucifer wasn't above doing such a thing, but it wasn't pleasant to dwell on.

The table in the war room became more cluttered as he began to work out his ideas. There were notes, and numbers, and variables, and eventually he'd gotten it figured out.

They had till May 18th to do something about the nephilim. That didn't give them a whole lot of time.

Sam's body ached from lack of sleep, and his tired mind kept making him think about things he'd rather remain left alone, like Lucifer and Gadreel, so now, even though he wasn't sure what else to do, he decided he was going to stay awake. He had to. It was better than attempting to get any rest because he knew he'd fail. Most nights were like that now. He'd resign himself to stay awake, because really, it was better than fighting a losing battle.