Overview of seed BH accretion and feedback in star-forming GMCs. (a) Initial condition, where the seed BH is inside a turbulent, pre-star-formation GMC. (b) Scenario where the self-gravity of the GMC (characterized by its mean surface density), star formation, and feedback dominate and disrupt the GMC, suppressing BH accretion. (c) Scenario where the GMC’s self-gravity is strong and gas is kept bound, creating a proper environment for BH accretion and feedback. (d) Scenario where the BH feedback is weak, and there is steady accretion flow towards the BH if it is at the center of the potential well. (e), (f), and (g) Strong feedback in different forms may suppress both BH accretion and star formation; this process is dominated by momentum outflow from BHs and can be approximated with the analytic argument as in Eq. (4).