  The recently confirmed correlation between the mass of SMBH and bulges of
galaxies (and their central velocity dispersion), suggest a common formation
scenario for galaxies and their central black holes. Common fueling can be
invoked through internal dynamical processes, external accretion, and
hierarchical merging of structures. The success of recent theories is reviewed,
as the self-regulated growth of both bulges and SMBHs, the predicted AGN
statistics, when activity is triggered by accretion and mergers, the predicted
frequency of binary SMBH and consequences. In particular, the SMBH growth
problem can now be revised, invoking intermediate-mass black holes (IMBH) as BH
seeds in the early universe. As a by-product, the merger of binary SMBHs help
to heat and destroy central stellar cusps. Remaining problems are mentioned.
