How to be the Villain When Every Character Likes Me

I was reincarnated into the Young Master of the Alsar dukedom, the villain of the novel "Romance in the Time Passing".

However, there was one problem. I had never read the novel, and the system that told me I must maintain the plotline wouldn't tell me anything! Without any knowledge of how to act as the villain, what the characters I had to bully looked like, or the basic norms of the world, I could only helplessly watch as the plotline veered further from its original.