Different state laws vary with regard to when someone who starts a fight may claim self-defense if the fight escalates to the point that he must use lethal force to escape it. If GZ is convicted, it will be because the jury felt he had some culpability for the initial conflict; Florida statute (but from what I read not the jury instructions) makes clear that even if George was 100% culpable for the initial conflict, he would still be entitled to use a gun in self-defense if Trayvon persisted in bashing his head in despite George's screaming.
If you recall Mark O'Mara or maybe it was West, wanted the Judge to insert that following someone is not illegal so therefore one can't use that as the initial conflict. The Judge said "Show me the LAW where it says it is NOT illegal. One of the lawyers said "Show me the LAW where it says it is." She refused to make that clarification. That is probably the hang up the Jury has. It will be interesting so see what their exact question is. More than likely she will just read the same law again.
I think that was what O'Mara was trying to establish with Witness Root when has asked Root to delineate the increasing stages of appropriate response in acts of violence.
I can't remember how that was spelled out in the jury instructions (I listened to them but cannot remember).
Bottom line, regardless of who initiated the argument, a fear of grievous bodily harm and potential death is a defense against murder 2 and manslaughter.
The prosecution was essentially advising the jury to ignore the law and the evidence and decide on "heart" (i.e. emotion).
If the jury is trying to tie the evidence to the applicable law...game over (I hope and pray).