The second of the shadowy planets, ketu stands for and governs the following:
Secret documents, secret love affairs, smugglers, spy and espionage activites, drug trafficking and prostitution, changes, imprisonment, miserly habits and meager amounts (as opposed to rahu), fires and explosions of severe nature, magic and witchcraft, intuition and clairvoyance, secret activities, secretive natures, extremes in good and bad characteristics, eccentricity, odd, different and wired, excesses, etc. Ketu also represents crime but of different sorts-mafia, underworld activites, terrorism, etc. it represents dons and mafia kings.
The various planets, as already discussed before, receive the influence of other planets that happen to conjoin or aspect them. Also planets own influences on native get modified by the zodiac sign that they occupy and also the nakshatra in which they lie.