I can't speak to the particular story (don't read SPN, haven't seen more than 1/2 of one episode! *g*), but it's the way of the WiP. The most comments usually seem to be the first and last parts, with perhaps an upswing on any installment with lots of hot sex. :D
I imagine there are a variety of reasons for it, but the upshot of it is that most chapters of a multi-part fic seem to follow that pattern in terms of their responses.
no subject
I imagine there are a variety of reasons for it, but the upshot of it is that most chapters of a multi-part fic seem to follow that pattern in terms of their responses.