Eric Miller wrote about the ‘politics of identity.’
‘Every interpersonal relationship is a political relationship, involving continual negotiation of the boundary between me and not me, of inline and outline.’
He was referring to processes of projection and introjection, which he translated into open systems language; ‘the individual exports chaos from inside and imports order from outside.’ He was also referring to Andrew Szmidla’s formulation of boundary transactions between systems, where what A thinks of itself (the inline) has to be broadly congruent with what B or C or D thinks of A (the outline), a shared reference without which communication is difficult.
See: E.J. Miller. (1979) The Politics of Involvement. Reprinted in Group Relations Reader 2, pp 383-398. 1985: A.K. Rice Institute.
This seems a good starting point for thinking about identity.