Jaywalker_Holmes

Ren, a modern doctor and a secret master magician, suddenly finds himself inside a random book he picked up at the airport...as the villainous older brother of the protagonist. As the bad guy, he's supposed to make life difficult for the Male Lead until the latter grows up and kills him in revenge. However, looking at the broken teenager in front of him, Ren can't help but feel his heart soften. 
Fang was an orphan who had never known what a family is. Abandoned at birth, all he knew was pain and fear. He loved nothing, and wanted nothing...until he saw the angelic Wade. To save Wade, Fang didn't hesitate to sacrifice himself. ..after all, there was no one to cry over him.
But then, Ren appeared and turned his world upside down.

The Villain Saves the Male Lead

They reached the caves soon enough, with Fang carrying Ren resolutely, despite the latter's protests. The three royals of the Dragon Nation were quite amused with their antics.

Fang finally put Ren down when they reached the entrance to the ancient caves.

"Ren shouldn't have a problem now," Prince Uno said. "The caves are more or less flat."

Ren didn't even know what to say to that.

"Come in, children," the Dragon Queen said, leading the younger ones inside.

"The magic is very rich in here," Ren murmured as they walked into the cave.

"Indeed," the Dragon Queen said. "These are our ancient ancestral caves, after all. Legend has it that the magic in the Dragon Nation originated from here."

Seeing that both Ren and Fang looked curious about that, she chuckled. "I shall show you the family library tomorrow," she promised. "You will find a lot of unique books there, which do not exist anywhere else in the world."

185 – The Golden Egg