The lion is the king of the jungle and as such in dreams indicates that you are a spiritual leader. If the lion is threatening, it means that someone abused their authority over you and this is now distorting your view of authority. In turn it affects your view of leaders and causes you to restrict your leadership ability. Spiritual leadership is where you empower others to deal with their own challenges.
A lion behind you means you used your spiritual leadership in a former life. As such it is very natural to you this time around.
A pride of lions can indicate pride is limiting your animal nature.