>>1Both. Subcultures form from a memetic core, a single narrative that explains the world and its future. At early stages the subculture often reflects the extreme fringe conflict with mainstream, flexible sets of beliefs and great potential for subcultural drift.
Instead of focusing on the expression of early subculture its far more productive to examine its roots and core beliefs. Media shapes and distorts the subculture by reporting on it and distributing information on the stereotypes and social norms within.
P.S. Read Maps of Meaning