And here are some random speculations on 9th house cusps and Mercury placements:
Aries - Engineering, technology, mechanics... something with practical appliance?
Taurus - Agriculture, economics... Design or other creative subject?
Gemini - Literature, languages, journalism, communication, information... Education?
Cancer - Social sciences, psychology, sociology... maybe history? Medicine? Education?
Leo - Political science maybe? Business/commerce?
Virgo - Mathematics, architecture, library science... anything detail oriented.
Libra - Fine arts, law, peace and conflict research... maybe business?
Scorpio - Deep, intensely focused study, regardless of subject. Maybe chemistry, biology, genetics? Neeing to figure out the mysteries of life? Psychology?
Sagittarius - Practical philosophy, theology, ethnology, foreign languages... Foreign exchanges?
Capricorn - Hard sciences. Engineering or mechanical sciences. Maybe business, law or medicine... for the status.
Aquarius - Physics, astronomy, mathematics... Computer science? Or maybe theoretical philosophy, gender studies, history of ideas...
Pisces - Medicine, biology, social sciences? Ecology, climate studies? Veterinary science?