Using HI spectroscopy, high-resolution imaging, and 15 new distances, we constrain the dynamical and dark matter masses for 24 reverberation-mapped AGN host galaxies. Within the HI radius, we find a typical mass fraction of Mdm/Mdyn = 64 ± 13%. We had previously found a strong correlation between Mbary - Mbh and we find a consistently strong correlation between Mdyn - Mbh, which suggests that black hole mass scales with the dark matter halo. We approximate Mhalo by scaling the HI radii and assuming a flat rotation curve out to the virial radius. We show good agreement with constraints from gravitational lensing and predictions from hydrodynamical simulations.