Hmmm. Woman being brutaly assaulted/raped. I would have to play this by ear. I guess the first thing to do is to size up the BG, and calculate my chances in a fight.
If they are to my liking, I would commence walking towards the scene, and order the BG to clear out in an authoritative manner. If he does, fine. If he gets up and decides to fight, beat the snot out of him, while doing as little permament damage as possible (get him unconscious as fast as possible).
If he ignores me, see previous action.
Then check the victim for injuries, and if necessary, place a 911 call. Then leave, without giving my name, before the LE shows up. Basicly play the anonymus hero.
If the chances of me winning the fight were not satisfactory, then make them so. Grab a tire iron/knife/bystander and execute the aformentioned actions.
The test of character is not 'hanging in' when you expect light at the end of the tunnel, but performance of duty, and persistence of example when you know no light is coming.
- Vice Admiral James Stockdale, USN (ret.)