My Senior Brother Can't Possibly Be a Demon Lord

[Cheerful, sunny transmigrated junior sister x brooding widower, reborn senior brother] [The blurb for my upcoming 1v2 older-brother-and-sister-in-law story, After the Ascended Immortal Lord Used Me and Cast Me Aside, is below] Mu Chun thought her senior brother had been acting strangely ever since he returned to the sect. Though he still cared for her as attentively as ever, she couldn't shake the feeling that something was off. The man who had always been strict and proper now disregarded the boundaries between men and women, acting as if there were no distance between them. The man who had always been warm and kind would suddenly reveal a vicious, murderous side. If she so much as neglected his feelings, he would seem to become another person entirely, acting erratically and irrationally. She diagnosed her senior brother with dissociative identity disorder. Then, one day, she accidentally fell under a love curse and ended up locked in a kiss with him. She discovered that his condition had actually gotten better. He no longer went mad. He just clung to her even more tightly. Held in his arms, her head spinning, Mu Chun instinctively tried to push away the chest pressed against her, but he caught her wrists and pinned them down, holding the back of her head in place. Her consciousness faded as their lips and tongues entwined. She thought that if kissing and hugging him could ease her senior brother's condition, then she supposed it wasn't so bad. Their relationship as senior brother and junior sister rapidly veered toward becoming cultivation partners. But Mu Chun accidentally discovered her senior brother's secret. Through his memories, she saw him fall to the demonic path, run her through the heart with his sword, slaughter living beings, betray the righteous path, and become a demon reviled by the world. The final memory showed him being reborn through a secret cultivation technique. Shocked by the truth, she stumbled backward, only to find herself pressed against a body as solid and cold as a wall. She glanced back. Her usually noble and immaculate senior brother had torn off his hypocritical mask, his gaze coiling around her like a vicious snake, binding her fast. “Xiao Chun, Xiao Chun… We are bound by fate across three lifetimes. Heaven destined us for each other. We are meant to share a bed in life and the same grave in death.” “Don't leave me. Don't betray me.” “Please…” - Shui Wuyue was reborn, returning to a time before everything began. Whenever he remembered Mu Chun lying in a pool of blood, his heart pierced by his sword in his previous life, he couldn't help but shudder. Since Heaven had given him another chance, he would seize it and rekindle his fate with his precious treasure. He loved the way Mu Chun depended on him, yet hated the way she grew distant and cold. Love, hate, anger, and obsession trapped him in a cage of agony from which he could not escape. To ensure their union ended happily this time, he had to suppress his greed and pretend to be the same noble, untainted man he had always been. He desperately tried to hide the memories buried in the past, but someone unearthed them. His false mask was ruthlessly ripped away. Shui Wuyue turned deathly pale when he realized Mu Chun had uncovered the truth. It was over. His carefully plotted plan to rekindle their fate had gone up in smoke. His Xiao Chun would leave him again. Reader tips: 1. The male lead is already deeply, intensely in love from the very beginning, and his love is rather obsessive. After losing his wife, he became mentally unstable and often says deranged things. 2. The male lead is no good. He's very bad, extremely bad, downright awful. 3. The female lead grows over time. She's weak at first, but gradually becomes stronger as she searches for divine artifacts. 4. The story is a slow burn, with an even split between plot and romance. The couple gets together in Chapter 43, and their falling-out happens after Chapter 58. Here's the blurb for my upcoming story next door, After the Ascended Immortal Lord Used Me and Cast Me Aside. Please add it to your collection QWQ [Blind, delicate orphan girl x aloof, otherworldly immortal lord of a brother-in-law / long-scheming younger brother-in-law] After Chen Huitao went blind, she felt that her husband had become somewhat different from before. He had always been aloof and uninterested in women, but now he took particular pleasure in tormenting her in bed, clinging to her with a fierce intensity. At the height of passion, he would even imitate her soft moans, leaving her flushed with embarrassment. He had once treated her like a discarded shoe, but now he showered her with care, sending all kinds of rare treasures and jewels to her courtyard as if they were water flowing from a stream. He used to hate her tears and complaints. Now that she had become steady and dignified, he seemed dissatisfied instead, finding all sorts of ways to tease and argue with her. Whenever he made her angry, though, he would tenderly kiss the tears on her cheek and murmur her childhood nickname. Chen Huitao paid little mind to any of this. She supposed her husband felt guilty because she was blind, or perhaps he had finally come around. Either way, it would be nice if they could live together in harmony from now on. Until one day, her husband invited a renowned physician to treat her eyes. She regained her sight, expecting to see her beloved's face again, but instead found herself unexpectedly looking into a pair of smiling, almond-shaped eyes. The man wasn't her husband. He was her husband's twin brother, her younger brother-in-law, Cui Shi'an. He regarded her with amusement. When he saw her stiffen, he pulled her into his arms and bit her ear affectionately. “Sister-in-law, did you enjoy spending your days and nights entangled with me?” - As Cui Shiyi prepared to ascend to immortality, there was only one person he couldn't stop worrying about: His blind, frail mortal wife. Fortunately, his twin brother Cui Shi'an had volunteered to look after his sister-in-law, so he could set this worry aside and focus on cultivating and overcoming his tribulation. Afraid his wife might worry, he didn't tell her he was about to face the tribulation. Instead, he secretly sought a divine physician and medicine to heal her old ailment, then left a letter for his younger brother to deliver to her. On the day he faced his tribulation and ascended, thunder roared. As his consciousness began to fade, the vision of his wife's beautiful face, radiant as a peach blossom, appeared in his mind and gave him the strength to withstand the lightning tribulation. Who could have guessed that, newly arrived at the immortal gates, he would lose his memories in the tribulation and forget everything about the mortal world? When he was summoned down to the mortal realm to eliminate evil spirits, he unexpectedly came across a loving couple. The woman's face looked strangely familiar And then, his memories burst forth. He stared at the couple's departing figures, his eyes nearly splitting with rage. That was his frail wife and his smooth-talking twin brother. Theme: Protect the people and uphold the righteous path