A multi-stage brush seal and assembly for sealing a circumferential gap with respect to a sealed component is disclosed. The brush seal includes a first stage including a first plurality of bristles and a second stage including a second plurality of bristles. In an embodiment, the first stage is configured with an initial first-stage clearance and seals said sealed component at high pressure and low pressure conditions, and the second stage is configured to have an initial second-stage clearance greater than the initial first-stage clearance so that the second stage does not seal said sealed component at the low pressure condition but is configured to be activated by a blow-down effect to seal said sealed component at the high pressure condition. In embodiments the brush seal includes features to enhance or reduce pressure blow-down with respect to the first-stage clearance.