Irony at z=6.68: a bright AGN with forbidden Fe emission and multi-component Balmer absorption

We present the deepest medium-resolution JWST/NIRSpec spectroscopy to date of a bright Little Red Dot (LRD) AGN, Irony at z=6.68. The data reveal broad Balmer emission from H$α$-H$δ$ and Balmer absorption in H$α$-H$ε$. The absorption lines are kinematically split: H$α$ is blueshifted while higher-order lines are redshifted suggesting complex gas kinematics; their relative ratios are inconsistent with a single, passive absorbing screen. The line depths require absorption of both the BLR and the continuum, ruling out a stellar origin, consistent with the smooth Balmer break. We fit the broad H$γ$-H$α$ lines and find the data favor a double-Gaussian effective profile, although exponential wings are evident. Depending on the adopted profile, single-epoch virial estimates give log(M_•/M_)=7.86-8.39 and λEdd=1.7-0.4. The dynamical mass implied by the narrow lines is low log(Mdyn/M_)=9.1, suggesting an overmassive black hole. The narrow lines display little attenuation, AV<0.5 mag; while broad H$α$/Hβ~9 and the broad Balmer decrements are inconsistent with standard dust attenuation curves, suggesting collisional processes. The forbidden-line spectrum includes auroral [S II] and [N II], and a forest of [Fe II] lines. Line ratios and kinematics indicate a stratified narrow-line region with both low (nₑ=420 cm⁻³) and high densities (nₑ 6.3×10⁵ cm⁻³). We detect metal absorption lines in both the optical (Ca II and Na I) and UV range (Fe II UV1-UV3). Our results support a picture of a compact AGN embedded in a dense, high covering-factor and stratified cocoon, with complex neutral-gas kinematics. While the choice of broad-line profile affects the virial estimates of M_•, we find the effect to be of order 0.6 dex between the different approaches.