Two paths of dark matter orbit interaction with the stellar bar (shown: x/y-plane). For simplicity, we approximate instantaneous halo orbits as 2D ovals in the frame corotating with the bar. Velocity arrows refer to the direction of precession of the dark matter orbits, and the acceleration arrows indicate the direction of acceleration of the dark matter orbits due to torque from the bar. Top: prograde dark matter orbit (dashed red line) being torqued by the bar (solid black line) until aligned. Bottom: retrograde dark matter halo orbit (dashed blue line) being torqued by the bar. This orbit will spend more time at right angles to the bar as shown in the rightmost panel.