Young Brother-in-law Is Now My Husband - Chapter 13: Calm Down Angry Bird!!

Ade has lived in an incense burner for over a thousand years, her days spent sleeping. Longing for the outside world she hears about from her fairy friends, her wish is finally granted when a man brings her home, releasing her from the seal. Ade, tears streaming, vows to repay her savior to the fullest extent.Qin Yu, known as the cold and ruthless Third Master Qin of Kyoto, finds his life upended when strange occurrences plague his bedroom after he places an antique incense burner given to him as a New Year's gift there. Chaos ensues, with items displaced and unexplained puddles of water; he even senses something in his bed while half-asleep.One afternoon, Qin Yu comes home early to find a young girl cleaning up spilled milk. The girl, her black hair cascading, her skin porcelain, is startled by his return and tries to flee. Upon being caught and questioned by Qin Yu, she timidly speaks of repaying her debt.To Qin Yu's amusement, she lists her belongings: pearls, antiques, even her savings. None of these interest Qin Yu, who instead sweeps her into his arms and suggests a more personal way of repaying the debt. Terrified, the girl's beautiful fish tail is revealed.

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.

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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

Back to the end of Ming Dynasty, he was reduced to a slave.

This emperor, a beggar can do it, a slave can do it, a bandit can do it, but a house slave can’t do it?

- Description from novelbuddy