Abstract: SO2 has been the biggest surprise from JWST’s early gas-giant spectra, providing insight into atmospheric metallicity, disequilibrium chemistry, and planet formation. I will share how this unexpected our exciting new results regarding detailed photochemical modeling of a new atmosphere grid, ranging from 0.3-1000x solar metallicity, 250-2000 K, and across a range of internal temperature, XUV irradiation, vertical diffusion, and elemental ratios. Our models reveal the ‘sulfur shoreline’ that determines the key, observable sulfur-bearing species in the atmospheres of giant exoplanets. For example, we find that expected SO2 abundances depend strongly on metallicity, C/O, and overall temperature; depend somewhat on XUV irradiation; depend weakly on Kzz (except for Teq ≲ 600 K); and are essentially independent of internal temperature. We also reveal the dominant sulfur-bearing species across this wide range parameter space. We show that despite its recent detection in a growing number of giant planets, SO2 is never the dominant sulfur-bearing molecule. These results have important implications for interpreting the growing trove of sulfur detections (and non-detections!) from JWST and for preparing for the even larger ARIEL survey.