  Pristine, atomically-cooled haloes may be the sites of primordial quasar
formation because atomic cooling triggers rapid baryon collapse that can create
10$^4$ - 10$^5$ M$_{\odot}$ black hole seeds. However, no numerical simulation
has ever followed the collapse of these haloes for the times required to form
supermassive stars and direct-collapse black holes (DCBHs). We have now modeled
baryon collapse in atomically-cooled haloes with a wide range of spin
parameters and assembly histories for times that are sufficient for DCBH
formation. Fragmentation of accretion disks after $\sim$ 500 kyr is nearly
ubiquitous in these haloes and in most cases leads to the formation of binary
or multiple supermassive stellar systems. They also confirm that rapid baryon
collapse proceeds for the times required for these stars to form DCBHs. Our
simulations suggest that binary or even multiple DCBH formation was the rule
rather than the exception in the primordial Universe.
