  The origins and mergers of supermassive black holes (BHs) remain a mystery.
We describe a scenario from a novel multi-physics simulation featuring rapid
($\lesssim 1\,$Myr) hyper-Eddington gas capture by a $\sim 1000\,{\rm
M}_{\odot}$ ``seed'' BH up to supermassive ($\gtrsim 10^{6}\,M_{\odot}$)
masses, in a massive, dense molecular cloud complex typical of high-redshift
starbursts. Due to the high cloud density, stellar feedback is inefficient and
most of the gas turns into stars in star clusters which rapidly merge
hierarchically, creating deep potential wells. Relatively low-mass BH seeds at
random positions can be ``captured'' by merging sub-clusters and migrate to the
center in $\sim1$ free-fall time (vastly faster than dynamical friction). This
also efficiently produces a paired BH binary with $\sim 0.1$\,pc separation.
The centrally-concentrated stellar density profile (akin to a ``proto-bulge'')
allows the cluster as a whole to capture and retain gas and build up a large
(pc-scale) circum-binary accretion disk with gas coherently funnelled to the
central BH (even when the BH radius of influence is small). The disk is
``hyper-magnetized'' and ``flux-frozen'': dominated by a toroidal magnetic
field with plasma $\beta \sim 10^{-3}$, with the fields amplified by
flux-freezing. This drives hyper-Eddington inflow rates $\gtrsim 1\,\rm M_\odot
yr^{-1}$, which also drive the two BHs to nearly-equal masses. The late-stage
system appears remarkably similar to recently-observed high-redshift ``little
red dots.'' This scenario can provide an explanation for rapid SMBH formation,
growth and mergers in high-redshift galaxies.
