12th house is a sensitive house, though 8th house is the most sensitive house. These houses are not natural malefic in nature, they are neutral houses and depends on other houses to give their results.
It is also noticeable these houses are darkest one, where 8th house is the most darkest. It represents rectum area and anus which is always hidden.
And 12th house is our feet, where the half part is visible and half not, sole while standing. It is the base of your body.
So, any planet in 12th house or its lord becomes our main base, and most important when it is our base then it does not appears to be giving results, it is hidden.
It is also the house of sleep, which means planet of 12th house gives rest to lagna. This rest can be death sometimes as well if acting bad, and also rest to soul is salvation.
Each and every planet has some god and bad results in every house, but any planet in 12th house becomes oversensitive. It is better that if these houses are vacant.
Though in 12th house Ketu is found to be best. But at same time it destroys married life, but not always.
It is observed that, Ketu should not be aspected by malefics like Saturn and Mars. Mandi and Gulik are not in 12th house. Then Ketu gives better results and best if aspected by a good Jupiter. If not, then Ketu in 12th will destroy your mental peace, enemies will trouble you, one faces big disease, problems in sleep, negative effect of paranormal activities.
Venus comes next to Ketu. Venus in 12th house can give very good results and sometimes very bad as well. If Venus in 12th and aspects by Saturn , it give detachment in married life, if by Mars it gives more attraction towards relationships. In Aries Lagna, Venus in 12th aspected by 8th lord Mars person is attracted more towards opposite sex, and cheating in relationship is also possible. But other conditions applies too. Don’t accept it blindly. Person goes for love marriage as well, with 12th Venus, also marriage happens suddenly. This 12th Venus gives good bed pleasure and if spritual combination is present then person able to control his/her lust as well.
Last best is Jupiter. These people have special gods grace, but they suffers also if Jupiter is in malefic influence. Jupiter in 12th gives good pilgrimage. He/she learns occult, and idealism is there base, if 2nd is not having Saturn influence. Head hair density on is low, and they tends to loose their hair early in life.