My Favorite Fictional Character Has Fallen to the Dark Side Again

[I don't think I've written this well. This is a trope I really love, and I want to do it justice, so I'm going back to think it over. I'll start once I'm ready.] Chu Jiao is sickly and spends her days in the hospital, never knowing how long she has left to live. To pass the time on her phone, she falls in love with someone. That someone is a character on a page. Sword's Return is a xianxia novel. The antagonist, Cen Fuxue, has suffered a tragic fate. During his turbulent youth, the heroine saved his life, and from then on, he fell for her. But the heroine has someone else in her heart. Cen Fuxue takes the heroine's life-bone and steals the Burning Flame for her, surviving countless brushes with death. Yet she tramples on him and abandons him. In the end, his heart meridians are too badly damaged, his internal organs are destroyed, and he falls into demonic cultivation. Chu Jiao watches with her own eyes as the boy goes from bold and spirited to gradually becoming meek, from proud and arrogant to a hunted stray dog pursued by the righteous sects. Her heart aches. She tosses and turns, as though she herself has lived through it all. Never in her wildest dreams did she expect that, after waking from surgery one day, Chu Jiao would find herself inside Sword's Return as a little spirit pet by Cen Fuxue's side. - At first, Chu Jiao has no other wish than for the paper character she loves most to be a little happier. With her fluffy paws, she clumsily sews a belt for him, wearing the pretty white fur on her body down to a bald patch. She risks her life to gather herbs for him, then uses up three years' worth of spiritual power treating his wounds. She does everything she can for him. She tries her best to bring a little fluffiness into his lonely, cold life. And so winter passes and summer comes. Chu Jiao cultivates a human form, and Cen Fuxue's demonic nature fades because of her. Chu Jiao thinks that even as a pet, she has finally earned a place in Cen Fuxue's heart. Until, in the Serpent Realm, she is gravely wounded and near death, yet Cen Fuxue still chooses to save the heroine first. At last, Chu Jiao sees where she stands. Her heart turns cold, its last warmth reduced to ashes. The heroine is the heroine. Cen Fuxue is destined to live for her, go mad for her, and die for her. She can't change the plot, and she can't save him. At peace with this, Chu Jiao shatters her inner core and finds a quiet place to let her body and soul perish. - But she doesn't know that she has returned to the twenty-first century. In the world she left behind, Cen Fuxue falls into demonic cultivation once more. Wherever the demon goes with his sword, rivers of blood flow. His name strikes terror into all who hear it. He kills 231 people from the righteous sects and searches for her for thirteen years. * In the bitter winter of the thirteenth year, his obsession drags her back into that world. Blurb written in June 2022 Theme: Stay positive and keep moving forward