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

With the matter of separate weddings settled, everyone calmed down.

Then Fang remembered Professor Luke's words about Rhea's birth and caught Ren's arm. "What was that about dark magic attaching at the time of Rhea's birth?" he demanded.

Ren sighed, but didn't evade the question. Hiding the truth from Fang at this point wouldn't serve any purpose anyway, he thought. So he explained in detail what had happened – the babies' raising an alarm, him splitting the babies into two groups – one set to stay with Fang and one set to go with him to the hospital, how they had grabbed Rhea from the incubator just before the dark magic tentacles could reach her and brought her back – and also how Ren had gone back to the hospital later and found a dark magic stone from his previous world, which he had sealed away.

262 – Uno's Hypothesis