I'm currently writing a villain who's meant to be extremely charismatic (he's a cult leader, after all) but by his own admission tends to creep people out at times. The way I'm thinking it's because a person, whether or not they know about his "leadership experience", can't help but pick up on something predatory in his mannerisms/the sense that he has ulterior motives. It shouldn't be a staple of every interaction with him (he's supposed to be likable so if everyone constantly got bad vibes from him it wouldn't fit that they seek out his presence), it should just shine through occasionally but brightly. I'm trying to avoid having the protagonist just outright state there's something wrong with the character ("There was just something off about him" "I got a bad feeling from him"). I know intuition and gut feelings are a thing that can usually be trusted, but personally when I read a character just magically "knowing" something about another character's morality based on a gut feeling, I can't help but feel it's a bit lazy on the author's part. I'm also trying to avoid it being too obvious that this guy is weird without the protagonist voicing that, for the reason I stated and because once you make it clear enough that a certain likable character isn't as they seem, then you run the risk of pressing the "obvious villain is OBVIOUS" button and making the protagonist look like an absolute idiot for not picking up on the signs. Any input is welcome!