Natal Rahu is the sign where your Rahu was placed during birth time, and from there other houses are calculated clock-wise.
If you were born with Rahu in Virgo, then your natal house is Virgo (Kanya Rasi) and during transit, MARS forming conjunction (in Virgo), sextile (aspect of 60° which are Cancer and Scorpio in this case), square (aspect of 90° which are Gemini and Sagittarius here), trine (aspect of 120° which are Taurus and Capricorn here), opposition (aspect of 180° which is Pisces here) are discussed in this article.
Conjunction is transiting through same sign as in birth chart, sextile is transiting 3rd or 11th house, trine is transiting 5th or 9th house, opposition is transiting 7th house from natal sign.
Transit Mercury conjunct Natal Rahu and Opposite Natal Ketu : The native tries to be aware of the popular cultural trends, attitudes and beliefs. The native is successful in conveying his ideas through advertising and publicity. The native tries to flow with the modern ways of living and intellectually adheres to the present cultural trends and view points. The individual due to his jolly nature, get mix ability, is very popular among friends, Coborns and neighbours.
Transit Mercury Sextile Natal Rahu and Trine Natal Ketu : The natives ideas and personal communications are in tune with the current popular trends, customs, beliefs and attitudes. The native is successful in public relations, advertising and contacts with the public in general. The individual’s dressing ability, living standards and eating habits reflect current vogues, and he is able to impress people around like group associates, Coborns, neighbours, and friends. The native successfully completes his business trips and assignments by the sheer ability to mould himself as the situation demands.
Transit Mercury Square Natal Rahu and Natal Ketu : The native’s ideas and communications tend to be out of harmony with the prevailing cultural trends, values and attitudes. The individual is critical of popular trends and social beliefs. At the same time he is also critical of conservative thoughts and traditional values because transit mars also square to natal Ketu. Social communications are often limited or cutoff some way. Not a good transit for public communication and relation and advertising etc. Under this transit it is hard for the native to decide which way to go. Potential of the natal chart is the only deciding factor.
Transit Mercury Trine Natal Rahu and Sextile Natal Ketu : The native successfully completes his business trips and assignments by the sheer ability to mould himself as the situation demands. Also successful in public relations, advertising and contacts with the public in general. The native is more conservative and shows greater intellectual interest in traditional cultural thoughts and values, and always tries to adjust himself and bridge between the two opposite poles. His success depends on the promises of the natal chart.
Transit Mercury opposite Natal Rahu and Conjunct Natal Ketu : The native tries to be aloof and out of tune of popular cultural trends, attitudes and beliefs. The individual is very conservative and tries to identify himself with the traditional values and view points. The native is of reserved nature and scarcely express his ideas and view points. The native is not a public man and usually refrains from communicating rather he tries to work in seclusion.