Hmmm, after re-reading, I think I might have to agree, but only maybe. Oryx and his siblings made a deal with very specific terms, and those terms never changed. However, if Akka was in charge, when we was broken by Oryx to gain the Tablets of Ruin, then maybe the terms changed. Or, alternatively, Oryx changed the deal when he spoke with the Darkness itself during his long retreat in the Deep. The Worms gave him some of their power initially, which came from the Darkness, but maybe Oryx just bypassed that and made a better bargain with the source itself. In any case, that doesn't quite satisfy my curiosity regarding the Books of Sorrow yet, as there is more I've probably missed on my first pass, and will need to coalesce in a second and third reading.