The Sickly Emperor Is Only Immune to Me - Chapter 114 - Defeat and Kill

In this school fantasy story set in the distant future, creatures contaminated by pollution have overtaken the land, forcing humanity to live in isolated mobile cities called Regios. One such city named Zuellni is a self-contained school in which freshman Layfon Alseif has just enrolled. Layfon reluctantly joins the 17th Military Arts Platoon led by the third-year student Nina Antalk and embarks on a series of adventures.

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

The human Race is at war with the Vicious Dalki and when they needed help more than ever, THEY started to come forward.

Humans who had hidden in the shadows for hundreds of years, people with abilities.

Some chose to share their knowledge to the rest of the world in hopes of winning the war, while others kept their abilities to themselves.

Quinn had lost everything to the war, his home, his family and the only thing he had inherited was a crummy old book that he couldn’t even open.

But when the book had finally opened, Quinn was granted a system and his whole life was turned around.

He completed quest after quest and became more powerful, until one day the system gave him a quest he wasn’t sure he could complete.

"It is time to feed!"
"You must drink human blood within 24 hours"
"Your HP will continue to decrease until the task has been completed"

Seven years ago, after their breakup, he disappeared without a trace.