Start with the Mangekyo Sharingan: Follow Lord Madara out of Konoha - Chapter 28: The Substitute, I Summon the Spirit

The ending of fairy tales is usually a happy ending of the hero and heroine. As for the supporting characters, who will care about their happiness? Having such a bad thought one day, they suddenly turn dark. They want to revolt, and they don’t want to be the main couple’s stepping stone for their ‘True love’ again. Oh my god! What’s about the plot? What kind of story will it play out with a character like this? Can it still run smoothly? The hero and the heroine are going to be crippled by the supporting character!!!!! Well, there’s actually a project to save the plot from it. By nipping the bud of all evil thoughts from them, and let the hero and heroine live together in happiness. The named of this project is ‘To save the supporting character’. All executors must dutifully do their work, and as for the mean to achieve it? Oh! That’s not worth mentioning~

No matter whether it is a white cat or black cat, if that cat can catch a mouse then it is a good cat.

- Description from Novelupdates

Her – a glutton without troubles or worries who crossed over and became a young fat chick with a deep vengefulness.

Him – a young master of the number one power; a two-faced man with elegance and charming, good looks; he is the chosen one of the former saint god and a man who will only bend his back for her alone.

This domineering crossover’s slogan is, ‘Don’t touch if it is this sister’s, put it there if it isn’t this sister’s!’

…watch how the Domineering Glutton and the Two-Faced Venerate Emperor create sparks as they meet and collide, stirring the whole Spirit Treasure Continent into turmoil, how they fall for each other and how they kill each other, how life and death severs love.

- Description from Novelupdates

Ryu Han-bin, the main character who fell into a new world after being chosen as a ‘suitable person’.

Because of the error in the guidelines, the training is repeated endlessly…

Luo Xuan traverses into a fantasy world and becomes a Celestial Emperor jointly resisted by the Righteous Alliance.At the beginning, he is sealed and refined within the Reincarnation Mirror, in a precarious situation.At the crucial moment, he counteracts the power of the Reincarnation Mirror to present the past.With the help of the past presentation, scenes from Luo Xuan's past are displayed before everyone's eyes.In his childhood, born with Double Pupils, he boldly declared that the Double Pupils are already an invincible path, and there is no need to rely on others' Venerable Bone when faced with such a craze.To save his sister, he resolutely transferred his Double Pupils to her, not for anything else, just because she is his sister!Faced with misunderstandings from the one he loves, in the empty grand hall, Luo Xuan ultimately utters a lonely sigh: What Empress Lord? I have always been your Luo Xuan.……After scenes from Luo Xuan's past are exposed.All the Empresses and leading women burst into tears!