Alternate chapter title: Baby's First Word.
I refuse to believe that Lucifer lost Lilith, fell from the celestial realm, ripped off his wings, birthed a full grown man, and then immediately decided to name his son. Nah, Satan came into the world knowing exactly who he was, and whether he knew it or not, he knows he's not Lucifer.
Satan was not completely surprised to find that Diavolo had exclusively called for Lucifer and Satan, leaving the other five brothers to wait in the palace elsewhere. He was surprised to be called to a different room, a guest bedroom, where the new being also resided. They had been cleaned of the blood, no doubt the work of a spell from Barbatos, and sat curled up in a corner of the room. Most of the furniture had been moved from the room making it feel very empty. Diavolo sat at the foot of the bed a few feet away from the small form in the corner, and his face flashed with relief upon their entrance.
"Thank you both. There is no one else more qualified to help navigate this… unique circumstance." Lucifer huffed at that, rolling his shoulders rather rigidly as well. Looks like I'm still a pain in his back. "Satan, you possess the experiences that grant knowledge that will be very helpful in guiding me through this. I know that you two have a somewhat strained relationship, Lucifer, but this is now a learning experience for all of us." The avatars of pride and wrath both stiffened as they subtly leaned away from each other. "Satan, based on your experience, what would you have me do now?"
He hadn't known what to expect when called upon by Lord Diavolo, but he certainly hadn't been ready for this. Lucifer's eyes burned into him, and he quickly had to temper the fire of wrath that ignited from the mere gaze. Looking once more at the prone form on the ground, he froze as those pale eyes met his. They looked so much like he had felt back then. Confused. Terrified. Overcome with something unnamed–something that flowed through them like blood. What are you? Mammon had gasped. Regardless of the blood that blurred his vision, he felt Lucifer's eyes on him in that moment, and he spoke the only word his mouth knew how to form. Satan.
Satan remembered believing he was a monster that belonged in a cage only to be bothered with when destruction was needed. What are you? He hadn't found an answer to that question for a long time. Maybe he was still searching. Slowly, he crouched to lower himself to the same level as the new being, and asked a revised question.
"Who are you?"
Satan had changed the question. Lucifer had tried so hard to push the memories of that day from his mind, but that was clearly no longer an option. Despite what the fourth born may like to believe, Lucifer remembered the day of his birth in painful detail. He remembered feeling those hands trying to push their way through his skin after he had ripped his wings from his back. He remembered trying so desperately to keep the wrath locked away deep inside, and obviously that only prolonged the horrifying process of expelling a demon from himself. This was why he urged Diavolo to let go once he saw the first imprint of shackled limbs under his skin. Satan was not the only one trying to change the narrative.
He remembered Mammon's gasped question which had led to the discovery of Satan's name which he himself hadn't even known–and Satan had been a part of Lucifer for centuries at that point. He had not known that the simple question would have caused enough of an impact on Satan for him to suggest a modified question for Diavolo's spawn.
As he and Diavolo watched their spawn who both had lowered themselves to the ground, his eyes wandered finally from Satan to the new creature when it seemed to be working its jaw for the first time other than to scream or make animalistic noises of agony.
"Baphomet." The voice was so quiet–so hushed compared to Diavolo's deep and hearty voice that boomed over crowds of demons. Looking closer now, he realized the similarities that the creature–Baphomet–shared with Diavolo. His form was small and slender, similar to that of Belphegor's, which Diavolo's broad muscles dwarfed easily. His hair was a dark black, eerily similar to Lucifer's own, with red streaks that matched Diavolo's spiky head of hair to an exact hue. Diavolo purposely kept his hair short and savoured his side-part against the recommendations of both Lucifer and Asmo. Baphomet had the same side part, but his hair was much longer running to rest on his shoulders. He would look very similar to Belphegor if not for the lack of bangs that concealed most of Belphie's face. Barbatos had dressed Baphomet in black pants and a red dress shirt, and Lucifer couldn't help the thought that Baphomet would terribly wrinkle the shirt with how he stayed curled up in the corner.
Diavolo joined Satan on the ground, but instead took to his knees. He rested his hands in his lap as he leaned forward slightly towards Baphomet. "Hello Baphomet. I am Diavolo." The royal demon looked over to Satan for a moment, seeing his unwavering eyes continue to stare at Baphomet. It seemed like the blond was lost in his head, looking for keen details or making connections between himself and Baphomet. Lucifer did not know what crossed Satan's mind constantly, but he knew that the young mind was not a simple one. Diavolo looked like he was thinking through his next words when Satan broke the silence with an uncharacteristically gentle tone.
Satan couldn't take his eyes off of Baphomet even as Lord Diavolo joined him on the ground. So often, Asmo and the other students of RAD picked apart his appearance to compare him with Lucifer. He couldn't exactly fault them. He had done the same many times–staring at himself in the mirror for hours at a time and at a portrait of Lucifer that hung in the front entrance of the house. The general conclusion that the others had come to was that he was so similarly different to Lucifer in every way. His green highlights in his irises and clothing were complimentary colours to Lucifer's red. His bright blond hair which hung over his forehead was similar yet opposite to the dark black hair that was brushed back out of Lucifer's face for the most part. It went deeper than Satan would have liked. Lucifer was right handed, Satan was left handed. Satan liked comfortable and laid back light clothing. Lucifer was always dressed ready for business and in black.
He noticed how Baphomet was different. Baphomet was a combination of both contrasting and identical parts of Diavolo with the red streaks of hair to prove it and darker skin than he or Lucifer who both had near white flushed skin. On the other hand, Diavolo and Baphomet could not be more opposite in their builds, eyes, and voices. Satan may have been the rejected parts of Lucifer–hence the contrasting traits he carried physically–but Baphomet was clearly a part of Diavolo that was not completely rejected. Something would forever connect the two, and Satan was yet to learn what. However, curiosity always got the better of him.
"What did you take from Diavolo?" Baphomet now looked over at Diavolo with fear in his eyes. There was fear very evident on his face, but something else. Something certain that gave Baphomet a stone cold expression. Once again, something that you could rarely see any trace of on Diavolo's face. Baphomet made no attempt to move his mouth again, and simply held Diavolo's gaze. Lucifer stepped closer behind them, and Satan could feel his powerful aura without turning to look.
"If you attempt to hurt anyone, we will be forced to contain you." Lucifer's cold words didn't seem to strike right with Diavolo, who turned to put a hand in front of the pride demon. Satan felt the wrath surge again, but this time allowed it to flow out in his words that were spit like venom at Lucifer.
"You are not making this better!" Baphomet flinched further into the corner at Satan's sudden outburst at Lucifer, and Diavolo did nothing to stop the blow he landed on Lucifer's knee which caused him to take a step back. Satan quickly turned back to Baphomet forgetting any possible consequences for his action. "You are confused. That is alright. We can all learn who you are. We do not want to cage you again."
The words flowed out of him naturally, and he turned when Diavolo set the hand not holding Lucifer back on his shoulder. "Whatever was done… there was no harm intended. I feel… better. He took the-" Diavolo stuttered as Baphomet winced and hid his face behind his knees. "He took the pain."
Can't guarantee that everything mentioned about Lucifer and Satan is 100% cannon. Some may be more HC, but nothing too important. Like, idk if Satan is actually left handed but whatever.