Mercury, when placed in the sphere of relating needs to analyse and discuss relationships, and they are often involved in verbal exchanges, debating, counselling, and sharing information. This person may excel at public relations or some kind of agency work. They are often successful in law, sales and there is sometimes a strong aptitude for psychology and understanding how others mentally tick.
Mercury in 7th house loves to have an audience to hear their ideas, and they appreciate verbal or written presentations done by others. They have a great interest in people, in general, and this often results in an understanding of what the public finds interesting their awareness and concerns. This person may even speak on behalf of others, and this is an excellent combination for those who work in mediation. It is through their connection with others that they become mentally stimulated. The individual may also enjoy studying one-to-one relationships, and find they want to help or advise other people with their problems.
This person needs intellectual stimulation in relationships, and they are drawn to intelligent and verbal people, with whom they can share their academic interests, and who they can learn with. The individual is usually involved in mercurial pursuits in partnerships or association with others. The major concern here is with communication and intellectual cooperation with others. Though, if they have little mental self-confidence in their own ideas and opinions they will let someone else do the thinking for them. They may even see others as being more intelligent and articulate than themselves. Planets in the 7th house can sometimes be given away to others, either consciously or unconsciously, as this sphere also rules our projections. Those with Mercury here are very concerned about what others think and will always seek mental companionship. The partner may be younger, or a relationship is formed through lots of written correspondence.
With Mercury in the 7th, many problems can be ‘worked through’ if they are discussed and analysed. Some people with this placement may be fairly (or should I say ‘unfairly’?) critical and judgmental about ‘those little things’ which their partner’s do which annoy them. Fortunately, the antics of the god of Mercury remind us that a sense of humour about such things is the great balancer.” By Howard Sasportas – The Twelve Houses
Those with Mercury in the 7th house can arouse interest from the public to the subject at hand. They can be vital in playing an intermediary role in helping people with information. Similarly, the individual has a lot to learn through their contact with others and being drawn to environments where people talk, share and exchange ideas are extremely important. Either way, there is much to learn, teach and communicate about. The ability to speak, write and develop communication with others needs to be cultivated.