>>31385
Well, I would say that it does not matter that much if one is tricked or agrees consciously. From the outside, it still looks the same. Anyone can add one line of narrative that "character got paid to do it" use some hypnosis, drugs or mind control gun LOL
So I guess you can agree that the main issue is not about consent or realism but about the fact of how victims react to torture and death.
While of course, it is uncommon to find people willing to die it is even more uncommon to find people who rape teenage girls and then invite their necrophiliac friends to fuck corpses devoured by dogs. Looks pretty cool but only happens in the wildest fantasies.

Considering your story scenario, In fact, this is totally possible for me to do. It also fits my preference of reverse domination when someone who appears weak dominates one who looks stronger. so the idea of the 13-year boy being the mastermind of the evil plan is great. It looks like the erotic verison of "Scott Tenorman Must Die" Southpark episode
It would be an opportunity to make a story with a very good and complex plot which has a bit more than just porn value.
It will count more as horror story than porn.

Although the idea of torturing and murdering little sister is not very appealing to me. I think some small changes can be made to make it more reasonable and simpler:
A single father marries a woman with 2 daughters who become his stepsisters and then everything more or less as you describe he is mistreated at home and school and gets revenge.
There may be some technical and logistic problems with that huge number of characters so it can be reduced to something more reasonable.
Since this seems to be a pretty long story I do not promise anything when it will be done if ever, but It will be on my list of plans.