In NC if a person instigates a fight they lose the right to defense by lethal force. Even if they are on the losing end of things in a bad way, they have no right to lethal force. The big guy might get charged with murder or manslaughter. However, if the little guy shoots the big guy he will get charged.
The big guy does become the agressor. However, that is legally different than the instigator.
That is how it is trained in CCH permit classes. That is also what I have been told by a police officer that is certified to instruct "civilians" (read armed guards and cch permit classes) on firearms and use of force.
Here's my credo: There are no good guns, There are no bad guns. A gun in the hands of a bad man is a bad thing. Any gun in the hands of a good man is no threat to anyone, except bad people.