Generally speaking, falling represents underlying fears and feelings of inadequacy and helplessness. Also, current difficulties, and situations in your life that seem to be on a downward spiral, especially those situations that seem outside of your control.
Dying usually points to a symbolic death. Old habits, attitudes that need to change.

Depending on your ages, it could be that you may be feeling your brother is doing something, or involved in something, and you fear that he may get into a lot of trouble.
It could be that you brother has started a new project or job that you fear he may fail at.
Either way you are concerned about your brother's well being, and you feel you have no control where he is concerned.

Hope this helps, good Luck!