What a fantastic character study of Martha and Donna. You've done an extraordinary job of revealing the "strata" of Martha's motives and emotions; the development of the central metaphor is superb and not at all overdone. Vivid, precise writing that really pulls in the reader: it's impossible not to feel for Martha and resent her and pity her (much as she does for Donna). And Jack is a perfect counterpart (I deeply love fics that deal with the Martha-Jack bond and play out their "aftermath" scenarios so effectively).