Mercury represents communication, Cartesian and logical spirit.
Mercury in Scorpio
Plays on words, argues, criticizes, jokes, is ironical, mocks. He is crafty and always finds a solution to a problem.
Weaknesses: mocks, derides, disputes, constantly picks a quarrel. A really awkward customer.
Mercury in III
Deep studies. Adaptable. He is attracted to the Arts/letters. He knows how to share ideas. Moves around a lot professionally. He can easily keep many irons in the fire at the same time.
664 Conjunction Sun - Mercury
He is intelligent and knows what he wants. Is a good organizer, he likes moving, travel. He likes literature.
-82 Square Mercury - Mars
While his spirit is lively, it is also cunning. He often acts without thinking, he throws himself into things and exaggerates - and this can bring certain problems. He is nervous and irascible. He can develop others' ideas, while they hesitate - he never does: he presses on.