Me, the Holy Emperor of the Righteous Path, Married the Demon Lord of the Evil Path?!

After ruling the Central Province Sacred Domain for a thousand years, Fan Chen was weary. The Heavenly Domain was in turmoil, plagued by troubles at home and abroad. Worst of all, the Silent Demon Venerable of the Northern Frontier was constantly making trouble for the Central Province: heartless, unjust, and utterly unreasonable. [Gravely wounded, he hid his identity and went to experience the mortal world. There he happened upon a gentle and beautiful mortal woman. By a twist of fate, he married her, and together they had a son and a daughter. He felt truly blessed by heaven. How could there be such a wonderful wife in the world?], Meng Buyu had held the Demon Venerable's position for three hundred years and was weary. Remnants of the old forces lingered, and corpse fiends were everywhere. Worst of all, the Emperor Hong Sage Sovereign of the Central Province made life miserable year after year: despicable, shameless, and utterly false. [Gravely wounded, she concealed her identity and sought to calm her demonic heart, but chanced upon a handsome, refined mortal scholar. By a twist of fate, they married, and together they had a son and a daughter. She felt truly blessed by heaven. How could there be such a perfect husband in the world?], Twenty years later, the two domains went to war. All living beings gazed up at the sky. Why had the Sage Sovereign and the Demon Venerable remained silent for so long? The Sacred Domain's holy son bowed, his expression awkward. “Mother, little sister.” The Heavenly Gate's holy maiden returned the greeting, her expression inscrutable. “Father, big brother.” The four guardians of the Sacred Domain, the four generals of the Demon Gate, the sixteen Wind and Rain Envoys, and the ninety-nine Watchers all fell silent as they looked toward their respective leaders... Your Majesty, why have you rebelled?!