Legends: The Emerald World - Chapter 22: Contract Closed

Earth is the human civilization’s cradle, but humans cannot possibly live within its cradle for eternity.In 2264, the first deep-space colonization spaceship of human civilization leaves the solar system and enters the boundless darkness…Zhang Yuan, son of the man behind the spaceship’s main control system, is one of the half a million volunteers to embark on the 20 light-year journey to a new planet.Follow Zhang Yuan on his journey of gaining new knowledge, exploring the unknown, and finding out what's the secret behind the intelligence enhancer his father left him.

Even after knowing what came next....I still accepted.A deal with the devil herself.A devil, in the form of a goddess.I accepted a life that I knew wouldn't end well, a life that was worse off than the very curel one I already lived.But I still choose to do it.I chose to become the villain.

Su Ran, a music prodigy, woke up transmigrated into a book.

At that point in time, the main story arc in the book had already been completed. As a villainess female supporting character, not only did she need to take over the original owner’s pitiful life in poverty, she also gained an instant son right at his rebellious period.

Ten or so more years from then, the son would turn into a twisted, evil villain. He would appear in one of the extra chapters to pick on the male and female lead’s children.

***

Su Ran: Son, you shouldn’t be too outstanding.
Su Han: Why not?
Su Ran: ’cause you will be killed.

Su Ran: Son, would you like to learn music from me and become a zen, little fairy boy who only needs to drink dew.
Su Han: No, I want to go into business so I can support you.

- Description from Novelupdates

High school student Misumi Makoto is called into a fantasy world by the god Tsukuyomi, in order to be a hero. However, the Goddess ruling the world isn’t as thrilled to have him there, and kicks him to the edge of the world. Tsukuyomi declares that Makoto is free to find his own way after Makoto is abandoned by the other Goddess.