Remember the good old days of Demon's Souls 4-1? Remember how the human player would summon phantoms to fight reds, while standing near those boulders and without ganging up on the reds? Here's a nice example of how you can host pvp without ganking people in Dark Souls:
Key thing is to stand on one of the hills, otherwise the red phantom will get spooked (I would). So not being a jerk is definitely possible in Dark Souls, as well. I'm not saying it's likely, though...
Also, this is my last post, cause of the awesome post count. :3