Help me to remember title of this novel... I'm looking for BL transmigration novel. Mc transmigrate to world where the villain still children. The villains is ML's nephew.. they have accident which killed villain's parent. So later ML take villain as a son. Villain really smart boy and kind of yandere. He likes to act sweet and cute but actually he just want attention. Mc has a nephew too, who later will be become heroine's first love. MC nephew is the one who knew that villains isn't really sweet and all his behavior is act.. Mc's Nephew is really smart and hate MC at the early stories. Sorry for my crooked english..
'I am the Father of the Villain' sounds very similar to what you're saying but I haven't read this novel.