Variation in emission line FWHM as a function of the change in continuum luminosity, for Hα, Hβ, Mg II, and C IV, respectively. No significant breathing effect is detected in Hα, Hβ, or Mg II, with regression slopes consistent with zero. A weak but statistically significant anti-breathing is observed in C IV. In each panel, the solid black line denotes the best-fit regression slope (with the best-fit slope and correlation coefficient R provided), and the error bar at the center represents the median statistical uncertainty of the data points. Interestingly, the Hβ panel shows a clear excess of data points in the upper-left and lower-right regions, suggesting that strong breathing is present in a small subset of pairs, even though the sample as a whole shows no average breathing signal.