Imagine three ideal clocks.
Clock A is on the surface of the Earth. The other two, B and C, are side-by-side in space, remotely distant from the Earth's gravitional well. As I understand it, clock A on the Earth's surface will be running slower than the two out in space, which will both be running at the same rate.
Now imagine that the two in space become separated. Clock B is tethered so stays the same distance from Earth. Clock C is not, and falls very slowly, picking up spee