A thing to remember here is that these posts are strictly meant for the particular planet position. Like, today we are looking at Rahu in Sagittarius, so the description given here may change for you if your Rahu is although in the sign of Sagittarius but with conjunction with or aspected by other planets. --

Rahu represents illusion, foreign lands, foreign things (foreign as in unknown things. So, for someone living in Punjab, culture and rituals of Kerala is also unknown and hence Foreign), Drugs, Medicines, any type of intoxication, fame, wealth, success, obsession, past-life left-over karma, movies, television, online world, cheating, imagined fears, unusual things, unique things, creativity, rule breaker. Rahu also blows things out of proportions.

Sagittarius is the 9th sign of zodiac belt, hence it represents many things related with the 9th house of horoscope like Religion, Knowledge, Wisdom, Higher Learnings, Gurus, Teachings from your Father etc. Besides it also represents Coaching, Universities, Professors and Preachers, Higher Wisdom, Written Law of the Land etc. Sagittarius has next set of 2 and half nakshatra which are Mula, Purva-Ashadha and Uttara-Ashadha. Sagittarius' lord is Jupiter.

One thing we have to remember with posts related with Rahu through Signs is that Rahu converts himself as the lord of the sign it is sitting in and then amplifies quality of lord. Like, when Rahu is in Sagittarius, Rahu will take all the qualities of Jupiter (Lord of Sagittarius) and then will amplify those qualities out of limit. Rahu also does same to the planet it is sitting with. Like, if Rahu is with Saturn then it will take all the qualities of Saturn and blow them out of proportion during Rahu MD or Saturn MD. It is always better to have Rahu alone in a house rather than conjunct with a planet. Another thing with Rahu is that recently I have come across of the view that Rahu and Ketu don't have aspects on 5th or 9th house, for the simple reason that they are shadow planets and for aspects you need a sight not shadow. I am yet to verify it on at least 50 charts, so for now I will continue with traditional approach of 5th and 9th aspects of Rahu. Ideal placement for Rahu is to sit with an exalted planet, then it takes all the qualities of the exalted planet and amplifies them.

When Rahu comes into Sagittarius, it now becomes obsessed with religion and philosophies. With this position, it becomes highly important to see the condition of Jupiter because if Jupiter is trashed somehow then this Rahu will get all the wrong and fundamentalist approach of religion. Also, as Rahu is about unique & creative things and Sagittarius is all about beliefs and religions, these people will go out of the way and learn about different religions and different belief systems and then preach about it. Also, they become quite unique in their approach towards God and may even be ready to setup their own religion. So, basically Rahu changes himself in every sign's character & traits and makes itself obsessive about it . This position also gives a weird spiritual thinking where people revolt against the traditional idea of Religion & God and make their own unique philosophy or even religion to approach or believe in God. There are two ways to look at the results of all these acts. Some people say that all these acts are paying them money in the end, hence they are doing it. I feel that money is the most natural outcome of any work. You do any work in this world and you will get money. There is no work in the world which doesn't pay you back. So, I feel that the basic fact that they are dedicating themselves to a higher cause is meaningful and most important. Money is an outcome which is bound to come.

Again, impact of Rahu's effect in Sagittarius will be controlled by the various nakshatra Rahu might be in. Like, if Rahu is in Moola nakshatra, its lord Ketu's position will effect Rahu. If Rahu is in Purva-Ashadha nakshatra, then Rahu is in nakshatra of Venus and we need to check Venus position. If Rahu is in Uttara-Ashadha nakshatra, then its lord Sun will impact Rahu.

Sign lord wise, Rahu is in Jupiter's sign, so as I said Jupiter will have the highest say on working of Rahu.