Wow the psychopaths are hard. I've died to Brandon like 10 times. I guess I need to bring some food in with me so I can heal. Right now I just have 3 assault rifles, a shotgun, a spiked bat, and a broadsword.
The guy on the bike kills me too. Any suggestions?
For brandon and the bike guy, you need fast weapons. I.e., a knife, modded gloves, etc. With brandon, hit twice with the gloves and dive away, else he will always hit you on the third or fouth shot. And keep moving so he doesn't surprise you. Also, it helps if you rescue the couple from the fire and bring them to the fight with you. The first time I beat Brandon, I gave the woman a pop gun and the guy a wrench. They kept Brandon distracted while I wacked away as his back with a laser sword. Brandon hacked them to bits, of course. But it was all for the greater good.
An easy (but cheap) way to beat the guy on the bike is to lure him into a maintenance room or get him stuck against one of the walls of the courtyard area of the mall (where you encounter him). His AI sucks balls, so he will get stuck and can't turn (best I can tell, the programmers didn't teach him how to back his bike up). Just walk up behind him and wack away. If you want to kill the guy on the bike in a legit way, grab a fast weapon and get ready to dodge. A lot. After you dodge him twice, he usually does a quick spin and then a pose. That's when you need to attack. Get in there, swipe once or twice, and then back away. wash, rinse, repeat.
For the chef, you need a gun with a ton of bullets, or a fast weapon and upgraded speed. The gun method is simple. Charge the chef, avoiding the plates. Once he whips out his sausage. . . er . . . frying pan, run away and start pelting him with bullets. He will run from station to station, gobbling food. Your gun has to be capable of delivering damage faster than he can heal. The machine gun works well, as does the explosive bow.
For melee, it is basically a matter of timing. Wack the chef until he runs to the first meat station. Run up behind him, wack a couple of times. then DODGE before he smacks you. Wash, rinse, repeat at the different stations until he is dead.