How would you build and roleplay an eldritch god, stuck in a mortal body, who's trying to start a cult of kindness?

The idea was taken from Tom Cardy's fantastic song, "Get Louis (Theroux)".

To prevent this character from being too one-note and reliant on the song, I imagine him to be like this:

He would be a journalist or private investigator or researcher who is completely unaware of the fact that they are an eldritch god. Every level that he would get signifies how he becomes 'stronger' and taps harder into his eldritch powers. They would investigate strange unnatural phenomena that occurs around them, while being an upstanding citizen in their downtime, helping others, donating to the poor and all that kind stuff. At night, the very people that he helps would secretly be converted into mindless worshippers - I'll work this bit out with the DM, but the idea is that he's exercising corruption on his surrounding. This corruption causes others to become kind and genuine instead of evil, but still eventually ends in them becoming thralls.

I can't figure out what class I want him to be though. Warlock seems obvious, but I wouldn't know which subclass. I also don't exactly know how this would work in combat. I like the idea that he'd passively cause magical effects to erupt around him during combat where his eldritch power would protect him, and he thinks that it's the stuff he's investigating. This brings to mind Wild Magic Sorc, but the rest of the class isn't too synergistic with the flavor I outlined above.

Any ideas or tips?