So, today I finally found that villain that will be woven into my series. I started working on the series in the summer. I figured out the ending (only to discover that the first trilogy was just the first part of the series...though idk how many books there will be at this time. Still trying to figure that out) to the first section of the series. Before we switch to brand new characters. The problem is this "villain" is 100% morally good. He isn't evil. He doesn't want power. He doesn't care about ruling the world. Or money. And he loves his black castle. He loves showing people around. He's got a wife, and children. And he's genuinely happy. AND yet he's corrupting people. But he's one of those guys whose too nice...but not fake. 100% genuine.

Here's my question: How do I flesh this out?? I'm FASCINATED by him. He's super interesting. But i'm not sure where to go from here. I know in my gut he's the over arching villain i've been searching for. But I have no idea what to do next...

How do you flesh out a villain?