You can never really know who a person is

Even if you talk with them in a clinical setting, people will ALWAYS hide parts of themselves. It's human nature, even if you want to deny it. That's why you should never judge someone based on how they look, where they live, or how wealthy/poor they are. Unfortunately, this often leads to tragedies, and we can only look to "red flags" to guess if something is going on.

Be careful out there, even someone you've "known" since childhood could be hiding some dark things.