Distribution of Gaia proper motion directions relative to the jet direction. The double-peaked structure shows that proper motions preferentially align with the jet axis. Colors encode the Gaia light curve trend (sign and strength), as in Figure 3. Nearly all sources follow the same pattern: fading flux drives the centroid downstream (0°), and rising flux drives it upstream (180°); see Section 3.2 for discussion. An interactive version of this figure is available at A. V. Plavin (2025).