Natal Neptune is the sign where your Neptune was placed during birth time, and from there other houses are calculated clock-wise.
If you were born with Neptune in Scorpio, then your natal house is Scorpio (Vrischika Rasi) and during transit, Rahu/Ketu forming conjunction (in Scorpio), sextile (aspect of 60° which are Capricorn and Virgo in this case), square (aspect of 90° which are Aquarius and Leo here), trine (aspect of 120° which are Pisces and Cancer here), opposition (aspect of 180° which is Taurus 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.
It takes 165 years for NEPTUNE to come back to its natal position and this transit is of not much importance to humans. But countries, states, big organizations can experience Transit Uranus conjunct Natal Uranus. Humans experience sextile, square, trine and opposition.
Transit Neptune conjunct Natal Pluto : Stimulation of latent, occult and intuitive faculties characterize this transit. There is change in awareness of the native. Some individuals may have telepathic experiences. The native tends to leave worn out emotional pattern. Important changes occur in the life of individual due to political, economic and social upheavals. There may be disputes over joint finances, corporate money, goods of the dead etc.
Transit Neptune Sextile Natal Pluto : New subconscious start characterizes this transit. An excellent transit for meditation and occult practice. The native may excel through science or technology. Social changes occur for the benefit of the individual. The native can use old and discarded material by transforming this into something useful.
Transit Neptune Square Natal Pluto : Tensions and compulsions characterize this transit. The native can use psychic forces for selfish purpose and there can be hallucinations. There may be danger through over indulgence in drugs or alcohol and through unwise psychic practices. Important changes occur in the life due to social, political and economic upheavals.
Transit Neptune Trine Natal Pluto : Regeneration of existing social, economic and political conditions characterize this transit. The native is engaged in completing a worth while cultural project with the cooperation and financial support of masses. The native may be benefited through corporate money, joint finances, inheritances etc. The native gets intuitive guidance in projects he undertakes. The native may be benefited from his insights in understanding scientific and spiritual laws.
Transit Neptune Opposition Natal Pluto : Increase in spiritual dimensions characterize this transit. Some person very dear to the native may leave for his heavenly abode and there may be transformations in the possessions. There may be total changes in life routines due to cultural, political and economic turn overs or natural disasters. In important relationships the native may find mysteries and intrigues. The native is psychically disturbed due to teasing subconscious memories. The native is not happy over his corporate affairs, joint finances inheritances etc.