amongst

fight among yourselves/ourselves/themselves

To argue or bicker within a certain group of people. I have nothing to do with this, so you guys can fight among yourselves.
See also: among, fight, ourselves, themselves, yourselves

put the cat amongst the pigeons

To do or say something that is likely to cause alarm, controversy, or unrest among a lot of people. Primarily heard in UK. The prime minister's casual remarks about the role of ethnicity in unemployment numbers has predictably put the cat amongst the pigeons on both sides of the political spectrum. We didn't want to put the cat amongst the pigeons, so we decided not to mention the bomb threat until we knew for certain that it was legitimate.
See also: amongst, cat, pigeon, put
Farlex Dictionary of Idioms.

fight amongst

or fight among
v.
To engage in mutual hostilities; squabble. Used reflexively: The siblings fought amongst themselves constantly. During our meetings, we always fight among ourselves.
See also: amongst, fight
The American Heritage® Dictionary of Phrasal Verbs.
See also:
  • fight among yourselves/ourselves/themselves
  • fight amongst
  • be first among equals
  • choose among
  • choose among (people or things)
  • apportion
  • apportion out
  • apportion out among
  • among
  • puppy love