Mercury in Scorpio – Interpreting Intense Feelings.
When mercury is in scorpio there is penetrating insight and also a tendency to use words to control outcomes, rather than to speak the truth. This is not always with an insidious intent, many times it is to comfort others.
But nonetheless – there can be erratic speech, but also a skill in interpreting emotional depth through writing and other activities where there is ample time to reflect on things.
A conflict arises between these two forces because Mercury is alight and fast energy, interested in flexibility and neutrality. Whereas Scorpio is about drama and passion.
The intersection of these forces can bring skill in interpreting difficult and intense moods and feelings, but may also bog down the speed of Mercury, necessary for clear thinking and speech, in the drama of feeling and emotion.
if not careful, the fearful, obsessed, quality of Scorpio can send mercury spinning off into story after to story, in an attempt to confirm the latest paranoid drama. These stories may be repeated to the objects of the obsession, or brought about to control 9even manipulate) the situation.
A better use of this function is to plunge into the realms of imagination and create something beautiful as a result. Mercury rules the 8th house from Scorpio, where paranoia itself may be transformed.
There is more information about Mercury here
There is more information about Scorpio here