Many people think that "dark matter" = "black holes." To the casually informed such equality makes sense. You can't see one, and the other you can't see into. Those who know a little more about the cosmos understand these are two very distinct phenomena.
Being two distinct phenomena also does not necessitate that all components must also be distinct. In this case, we commonly think of dark matter as being some sort of mysterious force/substance looming "out there," yet interacting with us through invisible gravity. Some components can be shared.
Artistic images abound of black holes as hungry beasts sucking up stars and gas. Artists illustrate this gravitational gluttony with identifiable baryonic matter, not with invisible dark matter. It is very easy for the casual mind to equate invisibility with non-presence and lack of interaction. There is a zone just outside a supermassive black hole's event horizon where identifiable objects revolve rapidly, due to the nearby great mass, and still stay outside. That visible action helps us locate the supermassive black hole itself.
Dark matter is primeval and fundamental for the structure of galaxies and galaxy clusters. It is found in all universes of the Multiverse. It is very stable, and thus predates our universe within the Universe.
I am primarily a taoistic energy/particle physicist. There is less and less evidence for more than four dimensions, and for branes (which are like membranes of separate dimensions). The two big news items in this area for 2014 are (1) the failure of BICEP2 to establish primary gravity waves during the earliest era of our universe; and (2) the likelihood that the much ballyhooed discovery of the Higgs boson is bogus, or of minimal significance in the big picture.
A revised LeSage view of the universe does not require more than four dimensions (l,w,h, and time), unlike fancy string theories with ten dimensions derived from General Relativity. Interestingly, Special Relativity was more Newtonian, also four dimensional. The only problem with Newton's world view: He didn't know what gravity itself is, just how it apparently behaves in near space.
It has been up to particle physicists to somewhat explain the essence of gravity. Before my formulation earlier this year, the best ideas came from Georges LeSage in the 18th century. Mr. LeSage's push (or shadow) theory fell apart in the 19th century as originally formulated, opening the door for ether models. My 21st century version corrects the error of using for gravitational force hyperluminal billiard-ball-like objects. I envisioned subluminal graviton flows to explain gravity.
Gravitons are also the pet of string theory. They are supposed to be massless (NOT) force carriers, able to travel between dimensional branes, as in worm holes created and energized by black holes. In this idea they work as tractor beams within spacetime curves, not as pushing streams.
This fantasy sets the stage for scientifically fraudulent movies such as Interstellar. It is shameful that some famous astrophysicists have gone "goo-goo-ga-ga" over the massively phony "science" in this movie. (The film makers couldn't even get right the size and color of corn plants in a long, global dust bowl.)
What then are actual gravitons, and how do they fit in with the reality of black holes? Gravitons are roughly circular, vibrating strings that constitute most of dark matter. Their individual size is about minus 37th power meters, too small to directly detect. There is another size dimension below gravitons, called the YY dimension. That's short for "YinYang." We know this concept from ancient Chinese philosophy. Yin is poetically expressed as the dark, female aspect of reality; and Yang is the light, expansive aspect. Through their interdependent dual natures, Yin and Yang together constitute the real nature of reality. Of course, we can't see and measure energy/particles at this dimension, as quantum theory points out, but you can envision them through a scientific Occam's Razor. Jonathan Swift said, "Vision is the art of seeing things invisible." Swift was talking about honest scientific vision, not hallucinatory vision, as in the movie Interstellar.
YY particles in the YY-size dimension are sequentially attached to, and detach from, vibrating gravitons. Individually, they are usually spherical. Their nature is to link together in linear chains. Launched strands of different length, and of different vibrational frequency, constitute different electromagnetic (EM) particles. Yes, photons (YY particle strands) do have some mass, which is why they are deflected by push gravity.
Attached YY particles are strongly bound to each other by "primary electromagnetism," which is not defined by plus and minus poles. YY particles tend to repel each other until they directly adhere. What we know on larger scales is "secondary magnetism," with electromagnetic poles. Interestingly, both types of particles have inherent poles, though only secondary magnetic particles apparently express this duality. The idea of primary EM provides us with a clue to understanding the strong force. The dialectical conversion on larger scales of primary EM into secondary EM provides a clue to understanding the weak force.
YY particles also float free in space everywhere in numbers beyond our comprehension. They are within baryonic matter, and they are within dark matter. You could say that our "empty space" universe is virtually filled with random YY particles moving in all directions at luminal or subluminal speeds within frames of reference. Such YY particles and their associated gravitons do not constitute anything like branes and extra dimensions.
Dark Matter = YY particles and gravitons, mostly. There is room for other items to inhabit dark matter, to a lesser degree. The scientists at CERN may soon find some of these lesser elements of dark matter. WIMPS are larger candidates currently in favor. CERN will never directly detect individual YY particles, due to their being approximately 1000 times smaller than gravitons. They may indirectly detect gravitons, as these are close below the Planck Limit of detectability.
Back to the topic at hand: Black hole cores can be composed of formerly baryonic matter AND so-called dark matter. The center of a persistent black hole is NOT a zero-dimensional singularity. It simply is a very compact mass of incredible density, where the inflow of gravity inside the event horizon is stronger than the outflow of photons. Only at the center of a big-bang black hole does the center mass implode to near zero dimensions, and instantaneously the yin of implosion flips to the yang of explosion.
The more massive the core, the more distant is its event horizon. Black hole event horizons are not perfectly spherical, because the internal forces are not perfectly smooth. Irregularity gives some opportunity for Hawking radiation just inside the event horizon to drain off the contents of the black hole. For very tiny black holes self extinction can be swift; and for supermassive black holes this radiation depletion could take many billions of years.
It is easy to imagine a singular and limited universe where radiation depletion over a trillion years could invite the victory of entropy over negentropy, according to the Second Law of Thermodynamics. However, Yin and Yang operate between and among many, possibly infinite, universes composing the Multiverse. The Law of Conservation of Energy and Matter ensures the balance of entropy (disorder) with negentropy (order) on the Universal level, even while entropy could win out for awhile within the local volume of individual universes.
Thus we see how the smallest energy/matter elements, the YY particles (at negative 40th power meters) also constitute in sum the great inter-universal reality (at positive 27th power, or greater, meters). The infinitesimal populates the seemingly infinite. The Multiverse is the Universe. Within this comprehensive picture black holes are an interesting local gravity phenomenon, but not very special. They are not the engines of intergalactic worm holes, and they do not mediate transport between branes in different dimensions comprising different universes. Anyone into theatrical science fiction who is disappointed by this reality should mentally pivot, and appreciate the greater glory of the real Multiverse Universe, including its infinitesimal components. We can still travel to other imagined universes instantly, with our minds. What our minds can envision, we may be able to create here. This way we can have our space alien visitations, and still retain a level of intellectual honesty.