it takes two to quarrel

proverb Two parties involved in a disagreement, argument, or fight are usually both responsible in some way (as opposed to it being the fault or responsibility of one alone). Your son blames mine for their fight at school, but it generally takes two to quarrel. Of course I'm the one who got in trouble, but it takes two to quarrel. It's not like I was arguing with myself! No, I don't fully believe either of them. I know it takes two to quarrel!