"Dark" energy and matter aren't necessarily actual objects or some special type of energy or matter, it's just stuff we can't detect with current technology. It's such a poorly overdone sci-fi trope that TV's imagination made us think it's some exotic thing. I mean it could just be matter and energy in tiny amounts floating in the vastness of open space. "Empty space" isn't actually a total void and it's more vast than most people can imagine.