The Mortal Realm was formed by the Immortal Deities of the Heaven Realm many millennia ago.
After that, there were only two realms, the Heaven realm, and the Mortal Realm.
The Deities in the Heaven Realm were proud and powerful, the two things most precious to them. Of course, they didn't want to lose either of them, neither their proud, not their power.
But things went wrong in the Heaven Realm when the Heaven Emperor fell in love with a female water demon. By the time he realized the truth behind her identity, she was already pregnant with his child.
The Heaven realm was in an uproar. Back at that time, the demons were not really too powerful and were scattered around in the two realms, but the Deities never liked them.
The demon baby was taken by the Heaven Empress in her care after the Heaven Emperor killed the female demon.
As the demon baby grew up he started realizing the difference between himself and the others around him.
Everything was going perfectly. Though the Deities didn't like the idea of a demon prince but they kept quiet for the time being.
But this was the silence before the storm. The day the Demon Prince turned eighteen, his demonic powers unleashed starting havoc in the Heaven Realm.
The Deities were worried that the Demonic powers of the Demon Prince would become a problem for them.
But then someone reasoned that he was only a weak demon with next to no powers, all alone in a realm of powerful deities. This blinded the Immortals from looking at the reality that was taking place in the very front of their eyes.
The Demon Prince wanted to learn cultivation just like his elder brother and younger sister but no one wanted to teach him. The Heaven Emperor and the Empress even prohibited him from going anywhere near the Imperial library.
It was always taken care of that he never ate anything that contained any kind of spiritual energy. There was not a single book in his chamber. He was forbidden from speaking to anyone. At the end of the day, he was confined in the four walls of his chamber.
As time kept passing, everyone in the Heaven realm forgot about the danger that the Demon Prince directed towards them.
Unknown to all those Immortals, the weak and stupid Demon Prince had changed a long time ago.
When he noticed how everyone around him was powerful, the Demon Prince was determined to surpass all of them and prove to his parents that he wasn't weak or stupid. That he could also become a powerful deity of the Heaven realm.
It took him years but he finally found a way to become powerful. It was a completely different way but all that he cared about at that time was becoming powerful.
It was an accident when he found one of the guards of the Heaven realm battling a seven feet tall three-headed serpent beast in the Cloud Array Mountain Peaks.
He had sneaked out of the Imperial palace just to come to the Cloud Array Mountain Peaks to see the very famous cloud arrays.
He never imagined coming across a battle between a ferocious serpent beast and a weak guard who was badly injured.
He was going to help the guard in defeating the serpent beast and prove that he's not as weak as everyone thought, but unknown to him, his demonic powers were craving the darkness and the lust that wanted to devour everything.
By the time he came out of his blood lust, he had already killed the guard.
But he didn't stop there. Something inside him was urging him to consume the energy of the dead guard. He didn't find it repulsive but the problem was he had no idea about how to do that.
It didn't take him much time to follow his instinct. In less than a minute he had consumed all the spiritual energy of the dead guard. He wasn't sure about how he did that but the energy that entered his body was too good to let go.
He didn't kill the snake and let it take care of the body. After that day, many more incidents happened where he consumed the energy of some of the other guards who were badly injured from fighting with the beasts or sometimes practicing with the Deities and mostly working as their punching bags.
He didn't kill anyone again but the lust of blood and death was always there.
It was years later when he found a book about cultivation in his brother's study when he went to meet him. Though he didn't get to meet his brother that day but he succeeded in slipping out the book with him out of his study.
Somehow his brother never realized that a book had gone missing from his study.
But the problem was that the Demon Prince didn't know how to read. The book was completely useless for him.
He started spying on the guards and other workers of the palace when they all cultivated. It was a necessity for everyone in the Heaven realm to cultivate, everyone but him.
It took him months to finally learn a thing or two. He realized that not all the things that he learned was helpful for him.
Sometimes they worked, sometimes they didn't. All this time he was also trying to learn how to read.
It took him almost ten years to finally be able to more or less understand what was written in the book that he had stolen from his brother's study.
As time passed by, he came up with some of his own methods to raise his cultivation level. He added his own ideas to the already existing cultivation methods just like his instincts suggested to him. It was like his body was aware of what it needed.
He had always heard some of the deities and even servants of the palace calling him Demon but he never realized the meaning behind the word, until the day he came across that three-headed serpent beast once again.
The serpent was a Divine level demonic beast. It had reached that level of cultivation in the past few decades where he could transform into a human form.
Soon the dark secrets of the Heaven realm opened in front of the Demon Prince. The serpent was the spirit beast of his mother who was a powerful water demon.
When she found about the plan of the Heaven Emperor and realized that she was about to die, she transferred all her energy into the serpent to protect him from dying because of the spiritual bond, along with her.
It had always been waiting for the day when it could tell the Demon Prince all the truth about the murder of its master.
The Demon Prince was though angry but he wasn't impulsive.
He found more demons with the help of the serpent. The other demons were also like the previous him, weak, stupid, and useless.
He started training them along with him. Thousands of years passed and the number of demons increased. They became more powerful and smart. They were hiding in the depths of the poison valley of the Cloud Array Mountain Peaks, waiting for their Master's order.
The Demon Prince had decided a long time ago that he wanted the position of the Heaven Crown Prince which originally belonged to his Elder brother or in short, the true heir of the heavenly realm.
When finally the day arrived when the Crown Prince of Heaven Realm was going to be officially declared and crowned in front of the entire Heaven Realm, the Demon Prince decided to finally come out of the shadows.
To say that the day ended up with the grand hall of the Heavenly Imperial Palace full of blood and dead bodies of both deities and demons, won't plant a good picture in your mind. But sadly or maybe not, it was the truth.
The Heaven realm was unprepared for the ambush that happened after the Heaven Emperor declined to Crown the Demon Prince as the Crown Prince of the Heaven Realm.
The Deities had never faced a war before in their lives and the number of guards of the heaven realm looked nothing in front of hundreds of demons.
Both the parties faced losses on their parts but the Heaven Realm was shaken to their core. Though they somehow succeeded in catching all the demons along with the Demon Prince but due to some unknown reason they weren't able to kill most of them.
The Heaven Emperor prohibited anyone from harming the Demon Prince but he allowed them to find a way and kill the rest of the demons.
After weeks of searching and experimenting, nothing worked. The demons who were captured didn't die by any possible method, no matter how barbaric or brutal it was. Even the Demons were not aware of what was stopping them from dying even after suffering to such levels.