I think the worst things can happen to a person is addicting to the habit of emotional blackmail!
People who are usually either like to control others or insecurity, they will be using “emotional blackmail” to make others uncomfortable, anxious and fears, if you donot act according to their wishes
This can happen in any type of relationships- be in work, lovers, friends etc. This act is result from a tricky mind that act and pretend to be friendly ,honest and sometime as victimized.
This is a harmful act seems to be towards others. But it is actually towards themselves- creating self agitation, hatred and harm to ourselves than others. The self graphing mind can bring only sufferings.