1- Sadism often arises because of anger still held but suppressed from childhood hurts.
It is the wish to hurt or provoke a reaction often in someone we love. In waking life most of us are not capable of being sadistic, but in dreams we can do what we like, so sadism becomes acceptable.
2- It will obviously depend on whether we are being sadistic or if someone is being sadistic towards us as to the interpretation. We know that in dreams other people can represent parts of ourselves, so we need to consider whether we are causing ourselves harm deliberately or inadvertently.
We may feel that we wish to punish ourselves for some supposed misdemeanour and, as a displacement activity, we dream of sadistic behaviour.
The very fact that it is sadistic may also mean that it is masochistic - that is, self-involved.
3- Punishment can be the other side of compassion if we do not have the correct motivation: ‘It’s for your own good’. [1]
To dream of being attacked with malicious sadism indicates there is an implication of guilt over wrongdoing in your life. You need forgiveness. [2]
It is the wish to hurt or provoke a reaction – often in someone we love. In waking life most of us are not capable of being sadistic, but in dreams we can do what we like, so sadism becomes acceptable. [3]
If we have to be dominant and controlling in everyday life, the unconscious shows its need to be controlled by such dreams. [4]