Play second fiddle means to be treated as less important than someone or something. The violins, informally known as fiddles of an orchestra, are divided into two sections - the first violins play notes in a higher range than the second violins, and parts of the first violin usually have more of the main tune and are technically more difficult to play. This is the source of the idea that playing second fiddle involves a subordinate, less important role. The Real McCoy, Oxford University Press
Play second fiddle means to be treated as less important than someone or something. The violins, informally known as fiddles of an orchestra, are divided into two sections - the first violins play notes in a higher range than the second violins, and parts of the first violin usually have more of the main tune and are technically more difficult to play. This is the source of the idea that playing second fiddle involves a subordinate, less important role. The Real McCoy, Oxford University Press