Can somebody give me some idea how to handle my fiance and his dad?

Okay, not sure what the freakin deal is but my fiance is a normal person really but get him and his father together and its like fight club! Both physical and verbal. When they get drunk its the worse......than after their fights 10 minutes later they are like best friends. His father is visiting him from Australia at the moment and its like trying to corral monkeys at a zoo=( What is the deal? How can I handle these two nuts for another week? My fiance has talked about us moving to Australia so he can be close to his family when we both finish school but I am starting to dread the prospects of that endeavor.