In my minds’ eye, I often consider gravity and photons as opposites. I don’t know when that happened – somewhere as a young teenager, reading science books. But as mathematically incorrect as it most likely is, it works for me.
Now they got Dark matter/energy and that’s fine too. But I still gotta go with gravity. I’d say neutrinos (I love neutrinos because of their barely-there-but-everywhere-ness) ’cause they’re the avoidant personality type like me smile emoticon but I gotta run with a photon <–> gravity spectrum, at least for my mental imagery.