I'm not a physicist, but...
...has anyone asked the question whether dark matter is actually matter at all? Hear me out.
The existence of dark matter is (someone correct me, please) is demonstrated by the gravitational effects of said matter on the universe around it. Now, gravity is looked at as distortion of space-time by the mass of an object...what I'm wondering is, given the recent news about gravity waves and possible permanent "damage" to space-time by particularly large gravitational events, what if the "effects" of dark matter isn't due to mass, but big bunches and wrinkles in space-time, like a tablecloth that hasn't been smoothed out. I don't know what would cause such bunching on such a scale, beyond leftover scarring from the big bang or something.
These wrinkles might appear to us as gravitational effects, wouldn't it? This could explain why dark matter hasn't been seen or identified yet, because there's not matter involved at all.
Again, qualifying my ideas here as the brainfarts of an old IT puke, without the benefit of any physics education beyond high school...feel free to tear it apart.