Rahu and Ketu are completely astral graha. They do not give any material results on their own. Their actual results are almost completely astral in nature. They influence the material only through the other planets they are linked to. Any placement of Rahu and Ketu will be influenced by the nature of the sign he is in, the owner of this sign and his power to give results and the other planets who conjoin/ aspect Rahu/Ketu.
If either of them are placed alone in the 8th house they perform very badly, this is because of their completely astral nature. The 8th house is quite cryptic to begin with and if either of these two are let loose here without any influence from the other planets the results can be quite devastating on the material front. They might give good occult and spiritual experiences but the effect on the physical personality and environment will not be good. Then the periods of these graha, as per the Vimhottari system, the Ketu Mahadasha or the Rahu Mahadasha will be fraught with dangers. Also it would be advisable to be careful during their sub-periods within other planets Mahadasha. Keep an eye on their transits too, as they last for a longish 1.5yrs/sign. However these will be very rare charts. But if you do get such charts also go through the characteristics of the Nakshatra that he is placed in. In these cases, the subtle influences of the lunar mansions will be stronger and should be given a look.
However Rahu or Ketu in the 8th house can give comparatively better effects if there is some planet with him or at the very least strongly aspecting him. So always first analyse this other planet and then the Rahu or Ketu. The negative effects of this placement can somewhat reduced if the ascendant sign/lord is highly powerful and capable of giving good results.
Rahu placed in the 8th house (Ketu in the 2nd house).
You will feel dissociated from your family, its resources, the family history etc. You might neglect the affairs of the second or handle them in a typically vague/disinterested manner or perhaps your birth family refuses to give you your share in the family wealth. There might be an undercurrent of bitterness and strain, try to be patient and sensible. Loss of wealth resources or their mismanagement is indicated. Avoid gambling and keep a monthly account of your earning/spending. There might be a tendency to be pessimistic and needlessly morbid. There is a good chance that would be some speech impediment or at the very least you will be misunderstood by others. Try to avoid swear words and unnecessary sarcasm and criticism. This was for Ketu in the 2nd house.
Now for Rahu in the 8th. If Rahu does not receive direction and beneficial influence from other planets this will be dangerous. Rahu will work in his ‘lower’ form and create scope for bad actions, criminal behaviour etc and the shadow side of the 8th will be channelised. The 8th house’s energies are very destructive and unless used wisely, these will cause several problems. Excessive uncontrolled desire to experience the 8this dangerous. 8th house briefly is physical death, release, separation, legacies, spirituality, longevity, organs of sex/reproduction, childbirth, surgeries, accidents, occult, tantra, deep thinking, movement of vital energy/kundalini, shocks, traumas, sudden changes, mysteries, perversity, deep-seated diseases, strange and not of this world.
If a properly directed and balanced Rahu is placed in the 8th then he will pull towards the secrets of the mind, the tantra, occult, the intangible powerful magics. You will be allowed access into these extra dimensions. He will also amplify the effects of the other planet who is influencing him and the effects of the sign and its lord. You can be really very good at all this esoteric stuff. But you will not be drawn towards organised religion, humanitarian views and will have differences with your Teacher-father. So try to develop your own life philosophy and stick to it. You can be very good at the professions indicated by the 8th, researchers, detectives, scientists, surgeons, financial wizards, explorers, travellers etc. Travelling might be extensive and more for pleasure than for work.
You can also gain from your spouse and his/her family, bequeaths and inheritance is quite possible. However when accepting these from others remain respectful and acknowledge them. Rahu is a pretender, so if you are not grateful about these assets from the dead/others you will suffer from bad karma. You will want to forge new identities for yourself, chameleon-like shifts in the personality can be triggered by Rahu. e.g you might want too many cosmetic surgeries and thus lose your self and also your assets. Be careful with such desires/urges linked to 8th house keywords. Do not over-reach. You might suffer secret diseases, problems in reproductive organs, if you are a woman then in childbirth too, accidents, surgeries and diseases related to over-heating. Basically the movement of pran/vital energy in the body will be highly changeable which will be the root cause of all your problems. Generally longevity is good, but then the other placements should also be considered before coming to a conclusion on the lifespan.
Ketu placed in the 8th house (Rahu in the 2ndhouse).
This is again a very sensitive placement. If there are benefic planets like Jupiter or Venus helping out this will work well else there will be problems.
You develop ambitions about increasing your wealth and assets and maintaining them for your use. Rahu in the 2nd manages to keep the family connection intact. There will be a desire to be in control of the family treasures and using them for your own purposes. You will want solidity, material things you can touch and increase. There will be intense desire for the material (Maya) but satisfaction can ultimately never come from the material. So do not get too obsessed about the gains and losses of the material. Accumulating money is good but try to put a limit to how much is enough and what ways are legal, keep your ambitions reasonable. Try to avoid criminal activities like cheating and bribery. You can be a good astrologer, banker or a singer/speaker. Will have a attractive voice and face. The desire is to experience all the keywords of the 2nd house. Over-indulgence and intoxication in the senses is possible, so limit your drink/ smoke intake and avoid drug intake. Rahu in the 2nd generally gives material comforts, but the problems start when you don’t consciously put a stop to his endless desires.
And on the other side, Ketu in the 8th, you have no desire to change, to transform and to re-invent yourself. The secrets of the mind, of the esoteric, the tantra, the intangible but powerful magics hold no charm for you in the present life. But you have experienced these mysteries to the fullest in your past lives and you carry with you the deepest learnings related to the 8th. You will not be aware of these. But if you can focus on them consciously, they will be available. If Ketu is working on his higher levels, he grants fearlessness. And this is not because of ignorance, it is from these past lives complete experience and learning. You are not scared of transformations of any sort. All professions indicated by the 8th house can be performed by Ketu in depth. The reproductive organs will be weak, so avoid promiscuous behaviour and keep yourself healthy. In case of any medical condition here, go to the doctor. Then the number of children will be less, especially male children may not be born or be short lived. The spouse’s family may be a drain on you and your assets, do not let them over-ride you.
Analysing Rahu and Ketu in this 2nd and 8th house axis can be quite challenging so take your time over it. If the Rahu/Ketu axis gets malefic influences or are debilitated, then there will be a reversal of fortune, situation can go from good to bad very fast. These two are eternally different, the desire to experience vs the apathy to experience. And the two houses in this axis are also completely different, the earthy and solid 2nd vs astral and emotional 8th. The 2nd house is bindings, Maya and 8this Moksh, release. When the Rahu/Ketu occupy these two signs, a balance is sought between mirror images which can be sometimes quite difficult to achieve.