Imagination Incarnate (Custom Made Demon King remix)

Demon Lord Offspring

Akros poked his head out of the shadows inside a familiar bedroom. One with a grand, massive bed and several jars containing black viscous fluid. A room none other than Lilith and Samael's chamber. Although it may be considered Lilith's only at this rate. Samael had been vacant for over a century, and Lilith had littered it with jars of Akros' semen. She was quite fascinated with the dense concentration of depravity within them. 

The succubus was sitting on the edge of the bed as Akros revealed himself from a dark corner. She didn't seem at all surprised by his presence, as her mana sense was transcendent. What surprised her was his actual appearance. 

"Akros, dear?" Lilith beckoned him closer. "Your form has changed drastically, as well as your mana signature. Did you promote to demon lord already?"

"Quite recently, in fact. If you're asking about the arms and my wings, then..." He scratched his nape with his usual guilty smile. "It's a long story. You got time?"

Akros told Lilith about his promotion trial, and his bodily changes. He mentioned how his blood was mutated from his exposure to radiation to justify Blood Fury. While this was the truth, Lilith found it very peculiar. 

"Is that so? I have spoken to other survivors of the human bombs since you left. Those demons did not have any such mutations. Instead they had radioactive magic and hardened skin or scales. You lack any such things. Perhaps you are, plain and simply, unique."

"Being the child of two demon kings would make me unique, I'm sure. I'm probably one of a kind due to the low fertility rate of demon kings, right?"

"Correct. You are the only child I have conceived, and as far as I know the only egg Asmodeus fertilized. I know not if other demon kings have successfully given birth to direct descendants, but I severely doubt it. You took many tries. Thankfully because of the low chance of pregnancy, Asmodeus did not suspect anything. I do not want to imagine what he would have done with you if I did not send you away..."

"On that topic, how long ago did you conceive me? I'm only around 52 years old, but when I met you 50 years ago, you made it seem like I was a relic from long ago."

"I turned heel on Asmodeus immediately after sending you away. That was..." Lilith made a thinking face. With great difficulty, she seemed to recall. "...around a millennia ago? Meaning-"

"I'm actually over 1,000 years old?" Akros sat down next to her, holding his head in disbelief. "That's insane. I must've been in that separate space for most of that time."

"Yes. Honestly, I still cannot figure out how you wound up in the upper Abyss. Although, you were likely born weak due to your egg not being fully developed when I extracted you from my womb. I apologize for that again. You must have struggled in the upper Abyss, your poor thing..." 

Lilith ran a hand through his silky black hair, sending a pleasant feeling through his body. Against her touch, he couldn't help but relax. "It was bearable. I survived through cunning and patience."

"Huh? Did you not use the array I gave you?" She looked at him with slight surprise and worry. "I spent days writing it for you..."

"W-wait a minute!" Akros suddenly lost the calm feeling he had mere seconds ago. His heart pounded out of his chest while his brain racked itself as he tried to comprehend what she said. "T-t-the system, was your- your doing?!"

"Yes. I named it the 'Custom Demon King System', I believe. I also implanted a fragment of my own soul to act as its operator and your guide. I hope you used it well?"

"..." Akros' jaw hit the floor.

The system was her doing. Lilith made the system. Her soul fragment... it all makes sense now! It wasn't isekai bullshit after all! Lyra's soul... was originally a fragment of Lilith's! I remember Lyra saying her soul was a fragment of a powerful unnamed demon back when we were constructing her body. Everything makes sense now. I'm not overpowered, I'm a miracle child. My system isn't isekai logic, it's a gift from my kind mother. I'm not a harem main character, I'm just the spawn of two demons who specialize with lust and charm. Man, I love tying up loose ends.