Mercury in hard aspect to Pluto is typical obsessive mind aspect full of penetration.
If you have Mercury in conjunction, opposition or square to Pluto in your birth chart, then you are the person who is a deep thinker. You don´t care about superficialities in conversations. You are the person who is not easily satisfied with simple answers. You believe that there is a lot more what can be discovered and searched. This position makes you great researcher, investigator, it´s great for someone who has to dig deep for answers and for someone who always questions everything.
Especially hard aspects become more challenging to deal with during your life. Hard aspects make you very suspicious about motives of other people. Even when there is no hidden agenda in something, you are someone who seeks it. You refuse to believe that sometimes things are the way they appear from the first glance. You are certainly not a person who believes in clear intentions of other people. You have big trust issues and sometimes you become entagled in your own world full of conspiracy theories. That´s why there will probably comes a day when your paranoia will haunt you.
You deeply believe that world is a dangerous place and that´s why you play your cards very close to your chest. You don´t share your plans with people. When you are asked about opinion on something, you are very cautious to share even opinions on trivial things. Your religion is somewhat dark. You are persuaded that you should watch your back in every situation. This mistrust of everyone and everything comes from early traumas. You have experienced big betrayal of trust. This might be from your parental figure or from someone very close to you. You may or may not remember the experience(s) but these are very deeply rooted in your subconscious mind.
Mind games are another favorite category for you. You are usually quiet person and don´t give away much info about you. You could be still for years on one topic but once you are triggered, then OMG! Your arguments are indubitable, they sting straight to the core of the matter. Another feature of yours are great manipulative skills. You are used to observe people´s behavior and use their weaknesses for you own benefit. You know exactly what to say to people to gain what you want. Furthermore, you make people believe that it was after all their idea! You probably believe that the only way how to gain what you long for, is to manipulate people. Sometimes you believe the current mask you wear so strongly, that you have hard times to recognize when it´s real you and when you only play needed character to gain the profit.
If you have this aspect in your chart, first step how to handle it is being aware of it. Just by awareness you can become more trusting to people not always having ulterior motives. Really, not everyone is planning to kill you.