Comparison of H I profile to C IVλ1549 Å and O Iλ1302 Å. The upper row shows the observed lines from the Xshooter spectrum (Wolf et al. 2024). The velocity zero point here is set at the H I line peak. The normalisation in each panel is adjusted to match at least part of the profile between the fitted H I profile and the line profile in the plotted spectrum. This highlights that the C IV is associated primarily with the BLR outflow and extends to higher velocities, while O I is more associated with the static rotating part of the BLR (the source of the deep absorption at multiple velocities across the line peak is unclear. The lower row shows the model predictions of the C IV (left) O I (right) profiles (independent normalisations), with the velocity zero point also set at the H I line peak. Details of how the predicted line profiles were created are given in Sects. 6.1 and 6.2.