Remnant production and retention in the NBODY7-computed, M_cl(0) ≈ 5.0 × 10⁴ M_⊙, r_h(0) ≈ 2 pc model cluster with all BH-progenitor stars paired in primordial binaries (see Sect. 4). In all the panels, “+MB” indicates the presence of such a population of massive primordial binaries; the absence of this symbol in a legend implies the case in which all stars are initially single. The F12-rapid remnant-formation prescription and Z = 0.0001 is assumed without (left column) and with (right column) PPSN/PSN. Top row: ZAMS mass vs. remnant mass (black filled squares) compared with the corresponding StarTrack outcomes from pure single-star evolution (blue solid lines; cf. Fig. 6). For the BH progenitors that have undergone a star-star merger before the BH formation, the ZAMS mass of the primary (the more massive of the members participating in the star-star merger, at the time of the merger) is plotted in the abscissa. For reference, the ZAMS mass-remnant mass points (orange empty squares) from an identical model cluster but with initially only single stars (as in Sect. 3; cf. Fig. 6) are also shown. Second row: natal and retained mass distributions of the BHs (steel blue and blue filled histograms, respectively; assuming the standard, fallback-controlled natal kicks). These are compared with the corresponding BH natal mass distribution without any massive primordial binaries (dashed empty histogram, cf. Fig. 8). Third row: cumulative time development of the total BH mass, M_BH, as they are born (steel blue solid line) and the total BH mass, M_BH, bound, that is bound to the cluster as a function of time (solid blue line). The M_BH(t) corresponding to initially only single stars is also shown (black, dashed line). Fourth row: same as the third row but for the BH numbers N_BH and N_BH, bound.