When you’re fighting in you’re dreams, it’s most likely due to an unresolved issue you have within your life. The fighting represents some sort of anger or hatred you have towards someone that you haven’t been able to express. Your mind is easing itself by allowing your pleasure zone to feel the power of fighting in your dreams, when you physically can’t. Your mind is pretty much tricking you in a healthy way allowing you do accomplish what you want, while resisting you from making a bad decision. The best thing to do is to solve your dilemma with this person(s), so your mind can be clear.
Killing someone you know in a dream is an act of aggression that you envision, but should NEVER act out. You may have been hurt by these individuals unintentionally or indirectly. No matter how much you hate a person in any kind of conflict, do not act upon dreams of hurting or killing them physically because it is not worth it.
Stop for a moment to think why you are dreaming of harmful dreams, or rather nightmares because a human life cannot be bought for any money or any material in this world; and simply irreplaceable.
Talk to them or ignore them all together and move on with your life. You are wasting energy hating someone, and dreaming of inflicting harm to them that causes you to lose sleep.