This is one of those ideas that came in fits and starts, where each attempt resulted in things quickly turning to mush. I finally realized that it needed to be a single line to allow one to follow what was going on. This piece is a bit longer than my other works but that length is necessary to allow things to play out.
The initial palindrome progressively has notes added to the row until it is filled, then notes are continuously removed by lengthening others, eventually returning to the original row.
The piece is scored for piano, though if brave performers can be found then it could be adapted for pretty much any instrumental duo.