I had the greatest showdown with another player in the last session I was in.
He had a bounty on him, so obviously my first decision was to kill him and claim the money. While chasing him, he gets into his Buzzard parked at the helipad near Vespucci Beach. I continue driving, and when he missed my car with one of his missiles I got out, grabbed my bullpup rifle, and shot him while he was in the chopper. I take the chopper, and he hides near one of the garage entrances, shooting RPG's and bullets at the chopper. The chopper breaks down (but doesn't get destroyed) while I have the cops on me and he attempts to kill me. I hide behind a wall, and he shoots at me. Barely avoiding death, I manage to kill him again using my sawed-off shotgun. A mugger (sent by a different player) robs me, and gets killed by another player. In the midst of the carnage my 'rival' sends a mugger out, this time I kill him and take the car I was attempting to get into.
I flee from the war-zone and he sends Merryweather mercenaries after me. Barely escaping, I stop at the outside of a mansion in Vinewood Hills (slightly north from Michael's) and fend off the mercenaries from there. He keeps driving around in his supercar and throws sticky bombs in hopes to kill me. I kill about 8 waves of mercenaries before attempting to make my getaway. I steal a Merryweather Mesa and attempt to escape, but due to the AI's ridiculous accuracy in drive-by shootings, I get killed after getting rammed by another Mesa. The mastermind behind the chaos left after the mercenaries killed me.
A couple of questions; Do Merryweather mercenaries spawn infinitely until their target is dead? Is it possible to evade the mercenaries somehow?