MTL - Mermaid Feeding Rules - Chapter 48

Our protagonist Caam is a man from Earth that was reincarnated into this world as a demon. In order to survive, he spared no effort in avoiding the sparks of battle and without noticing it, he became strong himself.

In a modern world where cultivators need a place to cultivate or vent their boredom, there are private businesses that set up instance dungeons with the aid of technology and cultivation magic to enable cultivators to train and commoners to experience the life of cultivation. They are called dungeon suppliers.
Xie Jin's one and only dream was to be a dungeon supplier and when his only relative passed away, the relative's inheritance gave him a plot of land and surprisingly, a 'System' Module which the relative had previously used.
With the help of the system, Xie Jin decided to pursue his dream of becoming the number one dungeon supplier.

Han Yun was spoiled from childhood.

He survived past his emperor dad and crown prince elder brother, and became an emperor.

He didn’t know how to govern the country, but he was lucky—there was a Grand Preceptor who “assisted” him, spoiling him even more than his father did.

After just a few years, this puppet emperor died. When he awakened, he had transmigrated into the modern world, becoming a third-rate model struggling alone without any loving parents.

Just when he thought he had become a little cabbage that nobody wanted and no one would ever spoil him again, a certain ancient monster of a Grand Preceptor who had lived 1,000 years appeared again… and looked to be doing quite well for himself.

The utterly impoverished little emperor had tears in his eyes: “Beloved subject! Zhen (royal We) have missed you so much!”

Grand Preceptor: “Your Majesty, this minister has waited for you for a thousand years.”

- Description from Novelupdates

When crossing over to multiple books, Ren Shuhan found that every protagonist Shou was waiting for him to start chasing them in the crematorium.

“Don’t waste your time waiting,” He advised sincerely, “There are more 0s than 1s, so I’m not going to chase someone that is not interested.”

The protagonist Shou (sneering): Oh, there will be a day where you’ll lick the ground I walk on.

After waiting and waiting…

Ren Shuhan: “This is the wedding invitation for my childhood friend and I’s wedding.”

On the wedding night, Ren Shuhan removed the veil: “Baby, I’ve come to marry you.”

“Don’t you know that life is nothing but a play where you are the male lead and I am just a supporting character?”

“I know, but I don’t care.”

He was smiling, but Jiang Qingyue wept.

- Description from Novelupdates