Not unexpectedly since it's about a teenaged girl who discovers she has synaesthesia, there's a little bit of overlap with Touching Indigo in terms of plot and characterization. But I think they're different enough that there might be room for both. Plus, Thea is significantly older than Mia and has a very different family background and dynamics, and things that are major subplots in Indigo are only minor ones in Mango or not really there at all (and vice versa). And, of course, my book has a major SF/Fantasy element whereas Wendy Mass's book doesn't. This is a relief, because I would hate to feel that all my ideas have been taken already, or that nobody would be able to read Indigo without making odious comparisons.
Meanwhile, Day Four has been a complete creative disaster, in spite of the trouble I took to drive the kids out to their grandparents' farm for the day so I could really knuckle down and get some work done. I still haven't decided what to do about my setting, my research list is sketchy at best, and I started my plot summary only to give up when I couldn't even decide on a decent Story Goal (i.e. the main point that all the characterization and action in the book is working towards). I know how Indigo started -- with the question, "What if someone had synaesthesia so intense that it screwed up her life and made everybody around her think she was crazy?" But that still doesn't tell me anything about The Point Of It All.
All I know is that I do not want to write yet another teen novel where a girl is ashamed of being weird and outcast and desperately wants to be ordinary and popular for a change, and tries for a while to pretend she's just like the popular girls at school but it all backfires, and in the end she learns that she is special and finds friends who are just like her and all is sunshine and butterflies. I for one am heartily sick of that particular YA motif.