The beginning of “mid90s” is comprised of sudden images cut together. Skateboards, still on the ground, are scattered with a force. A hallway where an older brother pounces on the younger one, pelting him with his fists. And the younger brother — the thirteen year-old boy we will come to know as Stevie — looks in the mirror and pokes at his bruised chest, then punches it, groaning with the pain.