The 3rd house governs the native’s siblings, including brothers and siblings, their relationships with the native, the native’s courage, writing skills, short-term journeys; Mercury’s placement in the 3rd house will bestow excellent writing and even speaking skills in the person.
Mercury in the 3rd house will give good relations of the native with their brothers and sisters; because Mercury is not a feminine planet (as opposed to Venus, for example), the native is likely to have brothers.
Furthermore, because Mercury from the 3rd house will also aspect the 9th house, which is the house of destiny, fortune, spiritual learning, long-distance journeys, relations with one’s preceptor, higher learning, etc., the person will also be gainful and earn very good wealth on the basis of their merit – and since it is Mercury, the gains will be through a field that includes writing or speaking or both, whether through business or job.
In the 3rd house, Mercury’s placement here will be beneficial more so to the siblings of the native than the native himself or herself. If the lord of the 3rd house of the chart is strong, the native’s siblings will have a long life and likely also have good health.
If afflicted, the health and lifespan of the native’s siblings will be affected. The native’s relationships with their brothers and/or sisters too may go bad, or they will not help the native during his/her times of need.
Some considerations to be made here are:
- Mercury in exaltation (Virgo) – for Mercury to be in exaltation in Virgo in the 3rd house, the ascendant of the native would be Cancer. So, when Mercury is in its exaltation sign in the 3rd house, the person or native shall be a very good writer and speaker, or in other words, he/she will know how to convince others and make a decent career or profession with writing and speaking. Additionally, Mercury here will also give excellent relations of the person with his/her brothers and sisters. Furthermore, Mercury in exaltation will also give courage to the individual since He will be strongly placed. The person also may have decent height and overall excellent lifespan.
- Mercury in His own sign (Gemini) – for Mercury to be in Gemini, the ascendant sign must be Aries; this placement of Mercury being in Gemini makes the person more courageous but also independent. He/she will not have much help or support from his/her brothers and sisters, or perhaps he/she will not need it. However, this placement will make the person extremely brave and he/she will be able to dominate the competition as well as crush their enemies.
- Mercury in debilitation (Pisces) – not much to be said here; the relations of the native get wrecked to some extent with their siblings, but he/she still has protection of destiny regardless so not too much goes wrong. The courage part may get affected though.
Additionally
- Mercury Rahu conjunction – Mercury Rahu conjunction in the third house will make the person very clever and skilful in communicating and deceiving others, since he/she will have the influence of Rahu in their logic and mind – and Rahu is never without His tools to trick the other parties. Such an individual may not enjoy good relations with his/her brothers and sisters, but he/she will be convincingly cunning as well as quite brave. He/she will be able to dominate enemies and achieve victory over them since Rahu also provides courage which is an element governed by the 3rd house.
- Mercury Ketu conjunction – Mercury Ketu conjunction is almost always a bad one due to opposing energies of Ketu’s spirituality and Mercury’s worldly interests. So, even if the conjunction happens with Mercury being exalted in Virgo or in His own sign in Gemini, the overall results would be likely negative in terms of wealth. However, the person may be a sacrificing person for their brothers and sisters (which is why they would be losing their wealth trying to help their brothers and sisters).
Aside from this, Mercury’s benefic effects would be well-expressed in its other conjunctions. Some quick explanations are given below:
- Mercury Moon conjunction – the native may have sisters or brothers, but they will likely look good and also enjoy a good lifespan
- Mercury Jupiter conjunction – this is an extremely beautiful conjunction and the native’s relationships with his/her siblings will be superb and the latter will also have a good lifespan and also be wealthy or financially well-off
- Mercury Mars conjunction – this will make the native quite intelligent and brave at the same time and his/her siblings would also embody those qualities, although there can be arguments or fights between the native and his/her siblings because of Mars’ fiery energies.
- Mercury Saturn conjunction – the native’s siblings will be intelligent and hardworking; the native will have occasional arguments with his/her siblings because of the strict nature of their siblings which will make the native feel restricted or constrained.
In three-planet conjunctions and beyond, the strength of each planet is considered and its effects on the house are likely the most prominent. For example, if we have a three-planet conjunction like Mercury Mars Rahu conjunction, then it will likely cause issues for the native because Mars and Rahu are enemies and also stronger in influence than Mercury who is a young planet. However, Rahu’s energies are greater than even that of Mars’, although if the zodiac sign of the house the three planets posited in are either Scorpio or Aries, then Mars will dominate Rahu while Mercury will simply develop the abilities of the stronger planet. In Aquarius and Capricorn, however, Rahu will dominate Mars. In Virgo and Gemini, Rahu will be stronger still.
So, in more complex conjunctions, the strength of the lord of the house as well as the affinity of the planets to the zodiac sign of the house that they are placed in matters.