Toxic people are notoriously hard to detect. While a psychopath will key your car and a sociopath will steal your girlfriend, a toxic person will subtly siphon your happiness through bad communication, forgetfulness, negativity, and disinterest in your feelings or opinions.
To find them, ask yourself Does this person add value to my life? Do they build me up as a person? If not, they may be toxic and unworthy of your companionship.
What if they’re inescapable, like a colleague or family member? Stay professional and friendly, but minimize your time with them; don’t show your neck to happiness vampires.
– Chris Butsch, The Millennial’s Guide to Making Happiness