Stellar density maps along the z-axis with a depth of 1 Mpc centred on the most massive halo of D9 at z = 0 in the REPOS (top), DYNMASS (bottom left), and DYNFRIC (bottom right) simulations. The panels are all 1 Mpc on a side. In each panel, we plot with dark-blue crosses the BHs located within the R_HMS of the associated sub-halo (the same criterion adopted in Sect. 5.1). BHs lying between R_HMS and 2R_HMS of the closest sub-halo are indicated with green crosses, while wandering BHs (defined as those located beyond 2R_HMS of the closest sub-halo) are shown as light-blue crosses. The values of R_HMS of the ten most massive structures correspond to the radii of the circles, each centre on the position of the corresponding sub-halo. The R_HMS of the BCG, in yellow, corresponds to the physical size of the yellow circle. The legend in the upper left panel of the plot shows the scaling size of the other sub-structures in the region, marked in white.