Dream about blackmailing someone indicates experimentation, invention, or eccentricity. You need to overcome your vulnerabilities. You may be looking down on a person. Your dream is a symbol for a problem or challenge that you are being confronted with in your life. You are keeping it all in instead of trying to deal with it.
Blackmailing someone dream states your high aspirations that may be way beyond your reach at the present moment. You need to turn to the your religion more. You want to be less inhibited and explore other areas of personality. Your dream is a message for feelings of insecurity or doubt. You are over-thinking things.
If you dreamt about blackmailing someone:
But the secret right now lies not in talking about how you are going to get things together, but actually doing it. Any time and effort will be well spent in doing all the practical things that have to be done in order to get your relationship to work.