Mass evolution and accretion rate for BH particles in different GMCs. In the first and third panels (from top to bottom), we select five BHs with significant mass growth from high-resolution simulations of the two complexes and plot the evolution of the mass bound to the BH (BH+disk, solid) and the BH-only mass (dashed). In the second and fourth panels, we show the accretion rate for the same BHs, each rescaled to its Eddington accretion rate ($f_{\mathrm{Edd}}={\dot{M}}_{\mathrm{BH}}/{\dot{M}}_{\mathrm{Edd}}$).