To have a same you need an other. To have a black, you need a white. To be an outsider, you need an insider. Hegel proposed this notion of dialectical opposites, which is in essence relative and relevant to our human lived experience. Why is it that in therapy an adult fifty something year old man with four grown children, may for example dread going back to his family home and "celebrating" the holidays with his siblings and elderly parents. In therapy his wife reports "my husband becomes a complete nervous wreck, stuttering over his words and hardly talking, as soon as we enter his family of origin home". She continues to explain when he is managing his business he is assertive, confident and a true leader; when he is out with his older children on a Sunday afternoon he is all smiles, laughter and completely relaxed. However once he revisits his childhood home he transforms into a different identity.
On reflection the man explained how within his family he was "the rebel" child growing up, and the more rebellious he appeared, the more "perfect" his younger brother became. It was almost as if they were in a dance. While the perfect brother evolved into his role of achieving at school, in sport and taking care of the family chores; the problem brother "evolved" in his role of failing at school, having no interest in sports and avoiding all household chores.
However only once the "perfect brother" left the family home to go to college, miraculously the other brother gradually began improving at school, being more involved in activities and even helping his parents around the home. We are always a sum of our parts and when a piece of the whole shifts the whole in turn shifts. Hegel had some insightful notions; to be an insider, you need an outsider.