How can one develop characters for character - driven novels?

Synopsis Kuramoto Daisuke, a freshman in High School was suddenly exposed to someone vanishing in front of him. Turns out he was admitted to a Special Class full of Isekai Heroes that were regularly summoned to Otherworlds since the start of their Middle School. He was told that he was to become their Support to prevent each of the Heroes' fate of dying in the world they were summoned into. Though mediocre, he realized that his ability has a great potential but it needs a lot of hard work on his part. Unconvinced of being just the Support Character, he vowed to excavate his mediocre ability, all the while supporting the Heroes using it. And maybe more. Join my Discord Server: https://discord.gg/BWBWUrU

A 20-year-old genius medical student transmigrated to a book she read during an experiment and became a female supporting character named Mo Li. In the book, Mo Li was originally a kind and good girl. However, she was framed and slandered by the white lotus female protagonist. In the end, she was betrayed and abandoned by her family. Her personality changed drastically, and she ended up in a tragedy. After understanding her situation, she decided to fight back and change her fate. Although she was only a medical student, her medical skills in the real world were 50 years ahead of those in the book world. Hence, with her unparalleled medical skills and his ability to foresee the plot… The brothers in the family who hated Mo Li initially all held Mo Li in their hands and treated her like a treasure in their palms. They all turned into crazy demons who doted on their younger sister. The leader of the underworld said, "Whoever dares to bully my sister, I will break his legs." The business genius's second brother, "My sister has a bad temper. If anyone dares to make her angry, I'll let him spend the rest of his life in the slums." The third brother of an international superstar, "I'm not free this month. Don't look for me for any activities. I want to spend the summer vacation with my sister." And the original female protagonist in the book finally met her opponent. After Mo Li exposed her various evil deeds time and time again, she eventually suffered the consequences of her own actions and was abandoned by everyone.

When Ye Qing Ran wakes up, she finds that she has transmigrated into a book. She has become the vain, domineering, and evil villain who dies a tragic death. Before she transmigrated into the book, she was the carefully groomed heir of the family. Her life goal was to make the family stand at the apex of the world of fame and fortune. After she transmigrated into the book, she does not want to participate in wars in the business world anymore. Every day, she would hit on chicks, torture trash, and flirt with handsome boys. But why do her father and three brothers look at her more and more lovingly? Father: "Whoever dares to say that I favor boys over girls, I'll make his family bankrupt." Big Brother: "My sister is the smartest and most suitable to be the heir." Second Brother: "My sister is invincible and cool. She is my idol." Brother San: "My sister is an angel. Our whole family is honored because of her."

An introverted girl has had enough of the isolation inadvertently formed by her solitary nature. Things changed when she discovers that she has the ability to transverse across the fabric of our universe into the dimensions of multiple storylines. Not only do these storylines leave her with invaluable lessons - they also impart a portion of their power - if she is deserving of it. The time has come for Zhao Youyue to change her fate. Never again, will she remain as a Side-Character!

Yan Xi, a medical prodigy who obtained a doctorate at the age of 22, never expected to end up transmigrating into a novel. Her husband was the female lead's fourth brother, Gu Shen. He was a bigshot in the business world who had suffered from disability from a young age and could only move in a wheelchair. However, he was a handsome man full of schemes. Yan Xi became the cannon fodder wife of a bigshot in the business world. Her first love, Zhang Ming, had stabbed her husband's subordinate with a knife. To force Gu Shen to release Zhang Ming, she had unhesitatingly to stab herself to threaten Gu Shen. Eventually, Gu Shen released the man and gave her a large sum of money. She took this money and eloped with Zhang Ming. After that, Zhang Ming planned for a car accident that ended her life as they hit the road, which allowed Zhang Ming to conveniently take her money and run far away. When she transmigrated over, Yan Xi found out that she had just stabbed herself with a knife and was in the critical stage of deciding her future fate! Therefore, when Gu Shen threw her the divorce agreement, Yan Xi decisively refused. "Hubby, I won't divorce you." Gu Shen was surprised by her change. "Have you thought it through? I've left you some real estate and cash. It's enough for you to live comfortably for the rest of your life." Yan Xi revealed a confident smile. "I've thought it through. Zhang Ming stabbed your men with a knife. You should hand this matter over to the law. I won't interfere anymore." The surprise that Yan Xi's change brought to Gu Shen did not end there. After that, she tore off the mask of her hypocritical best friend and calmly dealt with her scheming family members. She personally treated Gu Shen's chronic illness for many years. Bit by bit, she managed to shock everyone around her who was once prejudiced against her.

Dying and meeting a being who made him his new brother and promised to reincarnate him into the body of the strongest person of that world, what could go wrong with this right?....Well let's see how our protagonist deals with this when he finds himself inside a body that is destined to be strongest, which he will achieve no matter what. P.S.: It's not a serious story just a light read like a casual fanific about a guy reincarnating into Black Clover with some wishes.