A/N: This story takes place at the end of season one in 'Lucifer' and the beginning of season 13 in 'Supernatural'. The story completely disregards the last two seasons of 'Lucifer', as I have yet to see those seasons. Also, in order to fit this story, in 'Lucifer', Lucifer left Hell a few years earlier. He would've come to Earth just before Dean went to Hell.
Lucifer was down at the bar pouring himself a drink. The club would be opening soon and he needed to get a head start.
"Lucifer," came the voice of Lucifer's brother Amenadiel.
Lucifer rolled his eyes before turning to his older brother. The two of them had declared a sort of cease fire lately, but that didn't mean the angelic smug bastard didn't still annoy him. "Brother. It's so like you to show up just as I'm about to open. After all, it wouldn't be a good night for you unless you ruined mine."
"Luci, we have much to discuss," Amenadiel said seriously.
"I see," Lucifer said before taking a sip of his drink. "I can only guess this has to do with the escape of our dear mother."
"No, it has nothing to do with her," he said.
"Then I can't fathom what you think we'd need to discuss. You can't possibly be resuming your plan to persuade me to return to Hell," Lucifer said.
"No. Look, I hadn't planned to involve you in this. I didn't think the others would take it well. But things are getting worse, not better, and it is your mess to clean up," Amenadiel said.
Lucifer raised an eyebrow. "While the suspense certainly excites me, perhaps you ought to be less cryptic. What mess have a apparently caused?"
"Your little Frankenstein creation."
Lucifer scowled at his older brother when he realized what his brother was referring to. The creation Amenadiel spoke of hadn't been one of his better moments. Well, it had, but it hadn't. It freed him of a darkness that even he would agree was too much, but it also robbed him of a great deal of his power and posed a potential danger. "I'll thank you not bring that up again."
"I'd love to oblige, but it's escaped, again," Amenadiel said.
Lucifer's face darkened considerably. He wasn't sure what disturbed him more. His brother's declaration that the abomination he created had escaped, or that it had apparently happened once before. "What do you mean, again?"
"You didn't know about the first time?" Amenadiel said surprised.
"I don't know about any time. Speak!" Lucifer demanded loudly. This was bloody serious. It might even be more serious than his mother escaping from Hell.
"Well, your history got a bit skewered over the years," Amenadiel started.
"Oh, that much I know. Apparently, most demons were under the impression that the cage I created for that being was actually designed by Dad to hold me. I'll admit, it was quite entertaining to hear those rumors," Lucifer said. Only a few demons knew the truth. Maze, and maybe a handful of others.
"Demons weren't the only ones. Most angels also believed it, including Michael," Amenadiel said. Michael was his twin, and a bit more impulsive, as well as just plain stupid sometimes. Hence, he'd fallen for the rumors that their father had apparently locked Lucifer in a cage.
"Yes, well, Michael has always been idiotic. Get to the part where it escapes. That shouldn't be possible," Lucifer said. He'd been very thorough when he'd locked that bloody bastard up. There were many hoops that had to be jumped through in order to get that thing out.
"You know the prophesy about you and Michael fighting?" Amenadiel asked.
Lucifer snorted. "As though there needed to be a prophesy on that. I could never stand the wanker. It's obvious we'd fight."
"Anyway, Michael wanted to hurry it along. He wanted the fight to happen and create paradise. I tried to tell him he was picking a fight with the wrong person, but he wouldn't hear it," he explained.
"I go back to the bastard being idiotic. You're saying Michael got it released?" Lucifer asked with more than a bit of anger in his voice. If he ever got his hands on Michael, he'd punish the little idiot.
"He had help, but, yes. Before you even go there, Michael has already suffered for what he's done. He still is. Hunters got involved. They locked your creation back up, with Michael along for the ride," Amenadiel told him.
Lucifer laughed loudly. "Really. Michael's trapped in my cage. That's just bloody awesome. However, there is obviously more to this story or you wouldn't be telling it. And where was Dad when all this was happening?" He asked before pouring another drink and taking a sip.
Amenadiel sighed. "I don't know. He hasn't been to Heaven since your fall."
Lucifer sprayed the bar with the contents of his mouth. "What?!"
"I didn't want you to know. That's why I wanted to get you back to Hell. I feared what his reaction was going to be."
"This is just great. The bastard just took off?" Lucifer asked in shock.
Amenadiel nodded. "Anyway, things went down a couple of years ago. I'll spare you the details, but the thing was released again a couple of years ago."
"A couple of years. It has been out for years and you're just telling me?!" Lucifer asked angrily. They were all lucky the world was still standing. That thing was the worst of him. There was no telling what he planned to do.
"I told you, I thought it was better that you not be involved. Plus, I was convinced you knew the first time, and you didn't lift a finger to help. I didn't think you'd care," Amenadiel said.
"What could possibly lead you to believe that?! I locked the bloody bastard up, tightly! You thought I did that because I didn't care?" Lucifer asked in disbelief
"Does it even matter? We need to deal with this now. It'll only get worse, and it's already very bad. There's a lot more to tell, but we can discuss it later. You need to get ready to leave," he said.
"How much damage has it done?" Lucifer asked. He was going. He had no choice. Amenadiel was right, this was his mess. He needed to put an end to it.
"A lot. Lucifer, there's one more thing I think I should tell you now. I was debating it, but call it a motivator. It may have killed Gabriel," Amenadiel said.
If Lucifer seemed angry before, he was positively bloodthirsty now. If there was just one being in all the world that mattered to him, even more so than the lovely detective he'd become attached to, it was his baby brother, Gabriel. Gabriel may technically have been created by his father, but he would always, always be Lucifer's. There would be no helping anyone who hurt him. "What do you mean 'may have'. Is Gabriel dead?"
"He's said to be, but I'm not sure. Gabriel is good at tricking people. He might be alive," Amenadiel said.
"He'd better be," Lucifer said with the slightest twinge of pain laced in his voice. "I'll be ready soon. I'll call for you."
Amenadiel nodded and left.