In the beginning, there were two creatures, one of darkness and one of light. These creatures spent millennia experimenting with their powers trying to find and destroy their limits however they experimented alone and couldn't make any real progress until they used their powers together, creating our world. The Light created the ground, grass, and trees while the Darkness created the sky, sea, and wind. Over time they managed to create a small speck of a creature which sparked a creative frenzy. They created creatures ranging from simple insects to birds to deer to bears, to apes. Finally, they created three creatures that were completely different from all of the other creations. They had almost no hair and few skills that would keep them alive as they were as smart as a simple beast at that time. The Light was interested for only a few moments before leaving the strange creatures behind to work on new creatures, but the Darkness saw great promise in these creatures.
The Darkness chose to take a simple apple tree and implant copies of the Darkness's intelligence into it. One of the female creatures ate an apple and gained the knowledge of the Darkness; she soon abandoned the other two because she couldn't understand them and vice versa. After that, the Light became jealous and fearful so it created guardians that would later be called angels, the Light would then create a realm where it and the angels would remain and forbade any creature from eating the fruit of the tree.
The Darkness went to the first five angels to be created (Micheal, Gabriel, Raphael, Uriel, and Lucifer) to ask for a favor. Micheal and Raphael rejected the Darkness for fear that they would become tainted by listening to the Darkness, Gabriel and Uriel listened to the Darkness's offer but rejected the Darkness. Lucifer was the only one who agreed to help the Darkness, the Darkness wished to allow the new creatures to grow and needed someone to help.
The angel Lucifer took the form of a serpent and coaxed the remaining female of the new creature to eat an apple from the tree, she then let the male eat it. Both instantly became conscious and started to wander their home trying to make sense of what their existence was. When the Darkness and Lucifer returned to the Light's realm they were met with rage at what they had done and in that rage, the Light forced Lucifer to fall from the realm. Lucifer fell at such a speed that his wings and flesh began to burn until he was nothing more than a charred mimicry of what he used to be. The Darkness caught him before he died from the fall and in regret of what this experiment had cost Lucifer the Darkness created a realm where Lucifer could stay safe from the Light's wrath. These realms would later be named Heaven and Hell.