When the ruler of the fifth house is in the eighth house, this means that your hobbies may be unusual. For example, you may be interested in the occult, or researching the theories of what happens when a person dies.
You may be interested in reincarnation and the subjects that most people would not feel comfortable to discuss or research (because of such topics making them feel afraid, or because they are taboo subjects).
If this placement is afflicted, it can signify the death of a child, or that the child will be a dark character, like a criminal, for example. With such a placement, a child may become an occultist, astrologer, work in a banking sector, or manage other people’s money or property in some business or employment.
The ruler of the fifth house in the eighth house shows that the relationship with your child may be difficult. His behavior may cause you losses, and not only material ones. It could be a loss of time, loss of happiness, and so forth.
The child may often get into trouble, even a life-threatening one. He or she may go through a near-death experience. Your child may cause you to feel anxious.
Another meaning of this astrological combination is that your interests and hobbies may cause you losses, as well as sadness and unhappiness. So make sure your hobbies don’t harm you.
If this placement is afflicted, it could mean, for example, that you like engaging in secret love affairs, but this can even get you killed. If this placement is not afflicted, it can mean that you love engaging in activities that you don’t share with the world.