  (Abridged) This is the second of two companion papers on the interior
structure of self-similar accreting charged black holes. In the first paper,
the black hole was allowed to accrete only a single fluid of charged baryons.
In this second paper, the black hole is allowed to accrete in addition a
neutral fluid of almost non-interacting dark matter. Relativistic streaming
between outgoing baryons and ingoing dark matter leads to mass inflation near
the inner horizon. When enough dark matter has been accreted that the center of
mass frame near the inner horizon is ingoing, then mass inflation ceases and
the fluid collapses to a central singularity. A null singularity does not form
on the Cauchy horizon. Although the simultaneous presence of ingoing and
outgoing fluids near the inner horizon is essential to mass inflation, reducing
one or other of the ingoing dark matter or outgoing baryonic streams to a trace
relative to the other stream makes mass inflation more extreme, not the other
way round as one might naively have expected. Consequently, if the dark matter
has a finite cross-section for being absorbed into the baryonic fluid, then the
reduction of the amount of ingoing dark matter merely makes inflation more
extreme, the interior mass exponentiating more rapidly and to a larger value
before mass inflation ceases. However, if the dark matter absorption
cross-section is effectively infinite at high collision energy, so that the
ingoing dark matter stream disappears completely, then the outgoing baryonic
fluid can drop through the Cauchy horizon. In all cases, the solutions do not
depend on what happens in the infinite past or future. We discuss in some
detail the physical mechanism that drives mass inflation.
