In music theory, the dominant parallel is terminology used in German theory derived mainly from Hugo Riemann, Dp, in major, and dP, in minor, is the (US) relative to the dominant and is thus considered to have or fulfill the function of the dominant. Music theory is a field of study that describes the elements of music and includes the development and application of methods for analyzing and composing music, and the interrelationship between the notation of music and performance practice. ... Dr. Hugo Riemann (full name: Karl Wilhelm Julius Hugo Riemann) (July 18, 1849 - July 10, 1919) was a German musicologist. ... In music, the relative minor of a particular major key (or the relative major of a minor key) is the key which has the same key signature but a different tonic, as opposed to parallel minor or major, respectively. ... In music, the dominant is the fifth degree of the scale. ...
The chord can be seen as the "tonic parallel reversed" and is in a major key the same chord as the dominantparallel (Dp) and in a minor key equal to the subdominant parallel (sP); yet, it has another function.
For example, Am is the tonic parallel of C, thus, Em is the counter parallel of C. The usual parallel chord in a major key is a minor third below the root and the counter parallel is a major third above.
Both the parallel and the counter parallel have two notes in common with the tonic (Am and C share C and E; Em and C share E and G).