I am curious if stars (or other massive bodies) amplify or refract gravitational waves in a manner similar to the following.
In the case of amplification, do massive bodies affect gravitational waves similar to the steepening that occurs in shallow water waves during runup near shore? Or can massive bodies act like a pump to locally amplify (or damp) the waves?
In the case of refraction, I am wondering if massive bodies act like (in a very loose, analogous way) obstacles in water for water waves (e.g., see animation below)?
I realize that gravitational waves are quadrapolar, not mono- or dipolar but I do not think that renders them immune to similar effects if they truly are waves.
After some searching, the closest thing to an answer that I could find was a paper by Peters  that treats the index of refraction for gravitational waves as a scalar, which seems problematic for addressing a quadrapolar mode.