How serious is a fist fight?

Might be different for you in the US but over here, Police wont do crap unless its serious, if its just two kids having an argument and a fight breaks out, that shit goes on all the time. Its when it gets out of hand, like other people jumping in creating a full riot, or weapons being used the police will get involved.

If its about a girl, lol be the bigger man there aint a reason to fight, you have already won, its him that feels defeated.

Don't know how old you are, but I thought only adults could invoke charges on people. Maybe wrong there.

Avoid fighting at all costs, if it seems like this guy aint going to back down, make sure you have plenty of credable witnesses (ie noone with a record lol).

If the shit hits the fan, avoid going to the ground, kick him in the nuts, kick him in his shins, or punch him in the solar plexus.

Like I said, you already won, walk away, just don't turn your back.

Jam it back in, in the dark.