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

"Unhand Fang this instant," Ren said quietly, his eyes glowing like molten gold. There was an undercurrent of power and danger in his voice that was unmistakeable.

Wade blinked his big, round eyes in confusion, staring at his companion and Fang with a lost expression.

"Professor Luke? What's wrong?" he repeated, and then glanced at Fang's arm that had been grabbed by the professor. "Isn't it just a tattoo?"

Seeing that Professor Luke was still staring at Fang and hadn't let go of his arm, Ren forcefully grabbed Professor Luke's hand and threw him off.

"What is the meaning of this, Professor Luke? Not only have you been disrespectful and intrusive, now you have physically assaulted my fiancé," Ren hissed. "If you know what is good for you, go home, pack your bags and leave Cosmopolis right away. And never appear in front of Fang again!"

240 – Professor Luke’s Identity