User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-5604127-20130302213549/@comment-5929284-20130306153241

I think one thing that should be considered is Rick does actually have to write all these characters. He has to fit in enough character development, whilst still having the plot develop, while being detailed enough that us fans don't go B-S crazy. I mean, I think thats one of the reasons people take such a strong dislike to characters in the HoO books.. we spend much more time with them. I know the immediate response to that would be that he managed in the PJ series, but there are 4 more core characters in the HoO books. Grover and Thalia may get some more air time in the last book, but when it comes down to it, I find that one of the main points of HoO is that the 7 are totally isolated. They're having to deal with everything by themselves, and thats kind of a strength and a weakness.

Also, Rick does seem to favor keeping a structure in his books. He likes having a certain amount of POV's, and he likes keeping those centered around his main characters. I doubt he'll branch out and give a POV to a non-seven character. But I could be wrong :)