Astrologers write generic things about planets let us say it is Mercury.
When they write about it it's only 25% of what should be written and explained.
Mercury is a product or offspring of the Moon and adopted Son of Jupiter, it is called neuter or neutral it gives the result of its association with a malefic it is malefic, with benefic its benefic.
Suppose Mercury is lord of 2nd and in 7th with Saturn, as a second lord its Marak or killer, as lord of 2nd it's gone in 7th, it acquires the maraka quality from 7th house as well, here Saturn is lord of 9th and 10th therefore it cannot take over the Marak traits from Mercury because it does not own a trishadya or the 8th house.
As a second lord neutral mercury becomes, more neutral and thus will give the result of its association and the other sign, Mercury is adverse from both its sign so its result will be adverse for both the bhavas, the association of Saturn the 9th, and 10th lord with 2nd and 5th will create karak effects for Saturn but if the AD of Mercury is operative in Md of Saturn it will turn marak towards the end of its antar dasha, a planet can simultaneously be a Karak and Marak and can produce likewise results, so generalizing Mercury in signs or houses and then claiming it to be research is too farfetched and deceptive astrology.
