So, basically, this is what was happening in the Empty before "Bel" possessed Jack's body. Just to explain, this does briefly go back in time, set in the past kind of like a flashback; The following chapters will, once more, be set back in the present. ^^

Lucifer was losing it. Slowly, but surely, he was losing it. Somehow, this was even worse than the Cage; Even worse than sitting alone in complete isolation, hearing the flames crackle against the bars. At least, in Hell, there was a tiny bit of light; At least, in Hell, there were things to touch, to ground himself, to remember that he wasn't trapped in total nothingness, and so there had to be a way to break free. If he could touch it, he could break it. That was what he told himself. In here, however…?

He couldn't touch anything. It was an endless prison of darkness; Complete, total darkness. It didn't matter whether his eyes adjusted to it or not, there was nothing to see. He was alone, completely and truly, and he hated it. The Devil didn't think he'd be able to escape from this. He almost had - thanks to his vessel, Nick, the poor sap… but that had been foiled, interrupted, before he could get out. And that only made it worse; He'd had freedom right there, just within his reach, and it made him want it all the more. He couldn't stand isolation - but more than that, he couldn't stand being isolated in. Literally. Nothing.

At the moment, he was just walking. There had to be some kind of end - unless it was looping him around and around? Every part of him ached to leave, desperate to get out…

"Morning, Lucifer."

Lucifer jumped, whirling around at once - having been unable to interact with anything or anyone, of course it was a little surprising when he was suddenly being spoken to. It took a moment for his eyes to adjust - okay, that's a lie, it took a good five minutes of squinting and staring to be able to see who was standing in front of him. He recognized her, if only vaguely, and his eyebrows shot up the second he registered who she was. "Oh, hey… heeeyyyy, I know you." He snapped his fingers, taking a few steps forward. "Billie, right?"

Billie just nodded, ever so slowly, stoic and calm as ever. Lucifer raised his eyebrows, not moving his gaze from her. He was tense, wary, but oddly intrigued - and glad for the company, because damn, he had missed actually having contact with people more than he'd thought. He wasn't an overly social Devil, but it was still nice to talk to people every now and again… He pursed his lips, silent for a moment, then crossed his arms.

"So, uh, is there a reason to this social call?"

"Yeah, there is." … oh, that voice was familiar, in the worst way. Lucifer's entire body tensed up, slowly turning around to see who was there, and he inhaled slowly as his gaze rested on none other than his son. He was left spiraling, wondering when the hell he had even arrived - when he had died, hell, how he had died, as Jack glanced up at him. "Lucifer," he greeted, coldly.

"Son," Lucifer greeted back, somewhat uncertainly despite himself. He knew he had messed up beyond measure with the kid - and he had stopped trying to fix that a while ago. He ruined every other relationship he had with… well, pretty much anyone, and if it was already ruined…

Then why bother?

Of course he felt guilty. He felt guilty over most things that he did, the people that he hurt. He felt guilty for stealing his son's power; He felt guilty for abandoning his brother and Adam; Hell, in some stupid, twisted way, he felt guilty about Nick. There were only a few things he didn't feel guilty about - targeting the Winchesters, and rebelling. He felt justified, and extremely so, in those cases. But, in others… even if it had felt like he had no choice but to do the things that he did, like it wasn't really him making the decisions, but he was - he felt guilty beyond belief.

Which made him angry.

… which made him lash out even more. Which made him feel worse - and then he felt angry - you see the cycle here? It was endless. Lucifer's mistakes were endless.

"We need to talk, Lucifer," Billie spoke, brushing past Lucifer - the Devil leaned away slightly, though he didn't particularly mind the contact. If anything, a part of him somewhat ached for it, but his pride wouldn't let him admit that, wouldn't let him enjoy it. He watched, eyes narrowed faintly as Billie walked up to Jack, circling around him before stopping on his other side, facing Lucifer. "It's about your Father."

Lucifer quirked an eyebrow. Ah, so this was about God. But he had to wonder, what was the problem now, and why was his Father involved in the first place? Lucifer hadn't spoken to Him in… well, a while. Not since his alliance with the Winchesters, to defeat Amara. Not since his Father had actually apologized for the way He had wronged Lucifer, the things He had done - only to abandon him, yet again, the second Lucifer wasn't useful anymore.

The Devil narrowed his eyes, a small scowl settling across his face now. "I'm listening."

"I figured you were," Billie responded curtly, folding her arms across her chest and leaning back slightly on her feet. "Well, I'm not going to sugarcoat, so here it is; God opened every door in Hell, and now he's planning to leave. Find another playground, build another sandcastle." She arched an eyebrow at him expectantly, "if you catch my drift."

Lucifer just stared at her, torn between surprise and disgust. Tch, it was just like his Father, wasn't it, to just abandon His duties. Of course, the whole "opening every door in Hell" part was a little… odd? Not quite what he was expecting to hear. The Devil narrowed his eyes a little bit more. Honestly, it was kind of sad that the only thing he was surprised about was the idea of his Father opening the gates of Hell. Otherwise, the fact that He had left… honestly wasn't shocking when you considered who they were talking about. "'Kay?"

"Except, He hasn't left yet," it was Jack who was speaking now, a deep frown settled across his son's face. Lucifer's gaze flickered to him at once. "Billie said He's too weak right now."

"He is," Billie agreed, eyes narrowing. "For now. But not weak enough. As long as He remains in this universe, He's a threat. And not only that, He's thrown the Natural Order completely off balance. Souls that were once in Hell now roam the Earth. And your brother, Michael-" She paused, as Lucifer suddenly perked up, immediately gaining interest in the conversation. "-will soon be among them, as well. When I say every door in Hell, Lucifer…"

"You mean including the Cage." A slow smile was spreading across Lucifer's face despite himself. He would never admit it, but he sympathized with his brother and Adam quite a bit. The fact that they had just been left to rot - well, if anyone could understand what that felt like, it was Lucifer. As far as he remembered, though, Michael had been… well, to put it lightly, coo-coo for cocoa puffs. Hell, he was probably too far gone to even leave the Cage. Adam, on the other hand… well, while he might not be keen on separating from Michael, Lucifer was certain the demon would be able to overpower his brother in the weak state he was in. "Well, good for them. They can get some sunlight now," he noted, "they'll probably need the tan. Hellfire's not good for your skin, you know. Mm-mm."

A frustrated sigh broke through Jack's lips, but Billie was as patient as ever. "I didn't come here just to tell you how many problems your Father has just unraveled-"

"Sure, sure," Lucifer agreed distractedly, "that would take, phew, forever, I mean…"

"I came to ask for your help to stop Him."

That gave Lucifer pause. The Devil raised his eyebrows slightly, chin lifting just the slightest bit. Now, that most certainly intrigued him. Him? They wanted his help? Normally, Lucifer would have disagreed, but he stopped himself for two reasons. One being that this might be his last chance to get the fuck out of this absolute Hellhole of nothingness, and two…

Oh, the things he would do to get back at his Father.

He was being offered the chance to stop God - however the fuck that would happen - and he most certainly wasn't about to turn that chance down. Even his own freedom wasn't as tantalizingly tempting as this was. No, the chance to overpower God once and for all, to put an end to his horrible, selfish reign, the chance to prove that he was right all along and that God was, is, had always been and always would be the true villain, that overpowered everything. It was a chance, not only at revenge - but at justice.

And he'd be lying if he said that it didn't make him tingle all over.

"What do I have to do?" He finally asked, jumping straight into it - not even bothering to express his agreement, that was just a given; Billie had seemed to know exactly what to say to get him on board, and now it was just a matter of forming a plan.

"All will be explained before you leave," Billie replied simply, gesturing toward Jack, who narrowed his eyes at Lucifer ever so slightly, but didn't speak. "Jack has agreed to allow you in as a temporary host to his vessel for the time being. Keep in mind-" It was Billie's turn to narrow her eyes at Lucifer, now, who raised his eyebrows right back. "-he will be returning to his own body the moment we've secured your own vessel, and the moment Jack's soul is intact."

"Sure-" Lucifer cut himself off, stopping short, and turned his gaze back toward his son. The kid merely blinked at him, looking faintly confused by the abrupt pause, before Lucifer turned back to Billie. "Hang on, what's wrong with his soul?" He demanded.

Billie paused, exchanging a look with Jack - who, after a moment's hesitation, gave a confirming nod - before turning back to Lucifer once more. "It's… damaged. Almost to the point of nonexistence," she responded simply. "Jack is currently unable to hold a physical form in this state; He's hardly able to hold himself here, as is."

Lucifer stared at Jack for a moment longer, despising the concern that was lingering through him. He covered it up at once, narrowing his eyes and letting his gaze flick away from his son. "So I'm just a placeholder, then, until Jack's ready to leave," he muttered, putting as much spite into his tone as he possibly could, "I don't really know how I feel about that…"

Billie narrowed her eyes in response, calling his bluff right then and there. "You know just as well that it's more than that," she told him, her tone switching from calm to cold in an instant. "I told you everything will be explained, and it will. But you're either in, or you are out, from this moment forward. But if you want a chance to get out of here, and a chance to take your Father down…" She took a few steps forward. "Then you'll choose in."

Lucifer just fell silent, staring at her.

"So," Jack piped up, almost challengingly - Lucifer almost felt proud - as he tilted his head at the Devil and crossed his arms. "Are you in, or are you out?"

Billie quirked an eyebrow at Lucifer, waiting.

The Devil paused, slowly letting his gaze flicker back over to his son, before focusing back on Billie. This was… frustrating, to be completely honest. Every part of him ached to agree - every part of him wanted this, more than anything. If it weren't for his pride, he'd have already agreed by now - well, hell, he had, technically, kind of, sort of, not really, but…

Thinking about what was at stake… his freedom… his son… his sanity… his chance to prove himself right once and for all…

Fuck my pride, the Devil thought, hating himself all the more as he looked up again. "I'm in."

"Good." A grin finally cracked across Billie's face, and a very small smile appeared on Jack's - it wasn't much, but for some reason, it made Lucifer feel warm inside (which, in turn, made him want to bash his own head into a wall, except there were no walls to bash his head into). The grin vanished from Billie's face almost instantly, turning serious once more, as she narrowed her eyes at Lucifer again. "Oh, and another thing before we continue, Lucifer."

"Mm?"

"Nobody," Billie's eyes narrowed further, "and I do mean nobody can know. Prying ears. If the plan gets back to God, then He'll be five steps ahead of us and we'll be right back where we started. So you are to keep this to yourself, and only to yourself, am I clear?"

Lucifer's eyes narrowed slightly. Sure, he could work with that. "Crystal."