Lucifer fell with one third of the Angels of heaven.
Angels and Demons are inherently different.
Fallen Angels are inherently Angels.
It takes a long time, and a lot of evil, for an Angel to stop being an Angel.
It takes incalculable depravity for an Angel to become a Demon.
Since time immemorial, Angels and Demons have warred.
The greatest, and arguably only, victory the Demons ever won over the Angels was the fall of Lucifer.
One third of the Angels of heaven fell with her.
When Lucifer fell, those Angels lost their place in heaven and were chained in the darkness.
Making her home among the Demons of hell, Lucifer swore service to the Beast.
The Beast made the mistake of giving Lucifer command over one third of the Demons of hell.
The second rebellion, the rebellion in hell, happened much like the first, the rebellion in heaven, only things turned out quite different.
The ruler was cast down this time.
The Beast, Beelzebub, was cast into shadows.
Her High prosecutor was blinded and replaced by a fanatical avatar of pain.
And so Lucifer's rule began. If she could not rule in heaven, then she would rule in hell.
With her new High Prosecutor, Judgement, Lucifer's rule was unquestioned. All the supporters of Beelzebub fell away and were slaughtered, or simply vanished and hid themselves, otherwise they swore their allegiance to Lucifer, the new queen of hell.
The old High Prosecutor, Justice, was one of these that swore a new oath to the new queen. She was given a position high in the ranks of Lucifer's followers.
Lucifer's fanatical High prosecutor, Judgement, who carries out punishment of the sinful.
Lucifer's guard dog, Cerberus, who corrupts the natural world.
Lucifer's imps, Modeus, Malina, and Zdrada, who tempt humanity with wicked appetites.
Lucifer's secretary, Pandemonica, who observes and records all the Demons who follow Lucifer, and all those who do not.
And Lucifer's fist, Justice, who hunts down her enemies within hell.
Then he came.
The one who would walk through hell and challenge the might of the Demons and the Fallen Angels.
They called him the Helltaker.
After Lucifer and her Demons were taken from Hell, Beelzebub was free to return from the Abyss. And return she did.
"Plenty of Demons here, but none of them match the description of the Beast..." Arakiel idly fiddled with her fake horns, making sure they were stuck on snuggly. They didn't want anyone noticing that they were Angels. She glanced back to where her partner was sitting on the edge of a glowing pit of red hot tar. "Hey, what are you doing there? We've got a job to do here."
Turiel looked over her shoulder glumly. "We've been across all nine circles and seen neither hide nor hair of this Beast. We've been here so long, we're sure to have been missed from our post. God is surely angry with us."
"Look, that's not important." Arakiel thought about it for a second, then changed her mind. "Okay, it's not as important. Let Him be angry, I'm sure in the end He would rather Lucifer be in control of the fell powers than Beelzebub. We're just making sure the Beast isn't returning."
Standing up, Turiel brushed her clothes off with her hands and spade-shaped tail. "We've been looking for the Beast for so long and found nothing. Arakiel... I don't even know where we hid our halos anymore, and I can't break these horns off. I've spent so long among Demons, I... I think I've become one."
Arakiel shook her head. "No, no that's not possible. Angels can't turn into Demons." She put an arm around Turiel's shoulders and pulled her close. "Don't worry, I remember where we left our halos. It'll be fine."
"Lucifer became a Demon."
Stopping, Arakiel put on a grim face. "Okay, but that's different. Lucifer is a cursed devil. She rebelled and got what she rightly deserved when she was cast out. We're on a holy mission on behalf of God!"
"One that He never asked us to do. One that we decided to do all on our own. One that requires us to go against our standing orders."
"It's for His own good. Beelzebub is a far worse foe to face than Lucifer, and we're ensuring the Beast doesn't return."
"But there's absolutely no sign of the Beast or her forces anywhere."
"That's because we haven't looked long enough or hard enough. We need to investigate more closely."
"That's what got us into this mess."
"Look, the moment the Beast starts coming back, we'll be here to catch her. God will thank us."
"Somehow..." Turiel pondered quietly. "I get the feeling we should have stayed at our post."
"Shut up, shut up!." Arakiel waved at her frantically. "Something's happening." Addressing a finely tuned instrument she was holding, Arakiel grabbed Turiel and showed her the readings. "Demonic presence is increasing exponentially. Something powerful is getting close."
Looking at the device, Turiel frowned. "It reads like there's three high level Demons nearby. But that's within the margin of error, it's always showing one or two. We determined that's just the background demonic energies of Hell."
"Yeah, I know that's what Azazel told us, and it's been middling between one and two for a while now. It only just jumped to three." While the instrument didn't actually say how many of what kind of demon was nearby, they had been able to measure the power of different types of demons. The two little angels found this shift in the reading to be concerning, however, as they could not see any such powerful Demon anywhere.
Turiel stepped back, checking all around them to see if she could spot anything hiding itself nearby, but there was nothing to see. "If it's not close enough to see, then it's got to be..."
She was cut off as the ground began to split apart, knocking them both off their feet. From below, bursting into the open hellish air, a huge Demon pulled itself free of the stone. Standing tall, in his dark suit, his horns pointed to the sky, he looked down at the two Angels. His eyes burning with recognition, he reached down and grabbed them, lifting both of them into the air.
"Where is Azazel?" The voice that asked them was not one they would have imagined from this hulking brute of a Demon, but feminine and familiar. Like lightning, streaking out of the broken ground, a smaller Demon climbed up onto the shoulders of the big Demon, a white coat flowing behind her. She stared down at the two Angels through her red visor. "I'll ask again. Where is Azazel?"
Arakiel coughed, trying to put on a brave face in spite of how obviously easily this brute could crush her. "Uh, who's asking?"
"Why it should be obvious." The female Demon spread her arms out wide, standing high upon the shoulders of her servant. "I'm her. Call me Loremaster, the Science Demon, greatest scientific mind in Heaven and Hell, come here with my ultimate sin from the distant future with omens of disaster"
There was silence, which grew awkward, and then Turiel asked. "You're... Azazel... from the future?"
"Don't be silly. I said I'm her. My name is Loremaster. We may be the same person, but I am not Azazel. That little fool is going to make a great mistake soon. She'll begin her ascent among the ranks of the Demons of Hell until she's their ruler, overthrowing Lucifer just as Lucifer did Beelzebub. Unfortunately, while I managed to unlock every other piece of knowledge and shred of information the universe has to offer, it appears as though the Abyss is not technically a part of the universe. As such, Beelzebub was free to move without me seeing her."
"So what you're saying is... you fucked up." Arakiel summarized.
Loremaster grimaced. "Look, I knew to hide the time lab where she would find it last. However, my two best Demons had to keep her away so that myself and 67 here could escape to the past. Anyway, I need to find Azazel and get her to stop the Helltaker from disappearing. That's the cause of this whole disaster."
"Well that's going to be tough. Azazel disappeared herself a while back, and we don't know where to. A bunch of the most powerful Demons are also missing." Turiel cautioned.
Loremaster let out a sigh, then hopped down from 67's shoulders. "Drop them. There's no reason to squash them if they're already so far along in the transformation." She walked a few steps away as the Angels were dropped onto the ground, and stopped when she came to the fallen scientific instrument. "Ah, I remember this..." Scooping it up, she smacked it and watched the gauge shift around. "Curious, according to this reading, there is only three high level Demons nearby." She turned and held it up so she could see the others at the same time as the readings. "It seems as thought something has managed to elude my knowledge."
Arakiel took a step toward her. "Azazel-"
"Loremaster."
"Right... Loremaster... you should know that your being here has changed everything already, right? Your presence changes the entire universe exponentially, so whatever you remember happening has already been altered."
"Of course. Which is why I need to find Azazel."
"What are you going to do when you find her?" Turiel asked.
"She's already gone from Hell, and that means we have to be within the brief window where she is dwelling in the Helltaker's abode. There is not time to sufficiently explain to her, so I must do what I must do. I'll kill her and take her halo. Placing it back on my head should return me to my normal state, since it is mine. Yes, that should be enough. Then I will be able to prevent the Helltaker's disappearance, and Beelzebub will not return. How fitting that the final sacrifice I must make for science is my own past self..."
Achoo!
Justice handed yet another tissue over to Azazel. "Somebody must really like you if they're talking about you so much."
Taking the tissue, Azazel blew her nose into it, then tossed it into the trash can. "Don't be ridiculous. That's a silly Human myth and nobody actually believes it."
"What? No it's not." Justice lifted her sunglasses up to reveal her blind eyes. "I can't see normal things, but I can see things like curses just fine. One flies at you every time you sneeze."
"You're joking." Azazel looked at her, mortified. She knew Demons lied naturally, but Justice was so convincing. "Who would be cursing me?"
Justice just shrugged. "If I had to guess, I'd say your demonic future self who has set out to murder you."
"Whatever." The Angel rolled her eyes and turned back to the television in front of them. "Press A already so we can start."
"Okay! I'll beat you this time!"