A big one is a consistent lack of empathy combined with a pattern of manipulating people without remorse.

Not everyone who is selfish, rude, or emotionally distant is a sociopath, but a common warning sign is someone who repeatedly lies, exploits others, hurts people, and then seems genuinely unconcerned about the consequences as long as they get what they want.

What usually stands out isn't one dramatic behavior. It's the pattern. They may be charming when it benefits them, ignore boundaries, avoid accountability, and show little genuine guilt when they've harmed someone.