If Space is emptiness, what does gravity grab to bend it? (Strange Universe series)

We think of space as nothingness. Sure there is the occasional hydrogen or helium atom floating around in it, but we think of it as mostly an empty vacuum. But it must be something quite different from nothingness, because you can’t bend nothingness. It would look the same bent as straight. Since bent space around a massive object doesn’t behave like unbent space, obviously you can tell the difference between “bent” and “straight” space. So what is space, and what does gravity act on to bend it?

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This is a continuation in the Strange Universe series.
1—If photons have no mass, why are they affected by gravity?
2—What does it take to convert energy into mass?
3—How does the universe impose its fractal-like patterns of order on chaotic systems?
4—How small can the repetitive fractal features of nature get?
5—How can the most distant quasar be 28 Billion light years away?
6—Can nothing exist without the Universe?
7—How can order emerge out of chaos?
8—Where is the center of the Universe?
9—If CERN proves there are parallel universes, will you move?
10—If the universe expands at faster than the speed of light, does it begin to go back in time?
11—What is the expanding universe expanding into?
12—Big Bang Theory—How can you divide infinity into a single finite whole?
13—How would you answer this speed-of-light question?
14—What happens when the expansion of the Universe reaches the speed of light?
15—What’s your Strange Universe example to illustrate Sir Arthur Eddington’s quote?