Dreams involving animals, especially powerful ones like a black panther, can carry significant meaning. In your dream, sitting in the car with your brother suggests a shared journey or a relationship that is important to you. The panther's sudden entrance through the window could symbolize an unforeseen challenge or a powerful emotion that has burst into your life unexpectedly.

The fact that you anticipated the panther's arrival but felt unable to react may indicate feelings of being overwhelmed by a situation or emotion that you knew was coming but felt powerless to control. This could represent internal fears, stress, or an issue in your life that you are grappling with but have not yet addressed.

Consider reflecting on your relationship with your brother as well—there may be dynamics at play that are influencing your feelings of vulnerability in waking life.

To gain clarity, think about any current challenges or emotions that resonate with the imagery of the panther. This dream could be a prompt to confront what you may be avoiding or feeling unprepared for.