I agree that Sarah has great potential but the fact that's a creepy and ugly old man it's the problem, if only it was her son Aaron or as I said before, adding her brother would have made things way better since David also has a sister and seeing Sarah with her brother would develop the brother/sister part of this story better, Uncle Peter adds nothing to this plot since Sarah is already corrupted by David.
The uncle is there just to satisfy a request of a bunch of people that expressly requested that, nothing more, no one cared about the story, what Daval has created or anything else, they just wanted variety with an ugly-bastard and fuck off the rest.
Daval created a perfect setting already, if her son was in the place of the uncle, the story was 100% better and no one complained, because was right story wise, and when will be the turn of Aaron, the story is already ruined, Sarah will be an easy one that will fuck the entire family, will not be interesting because she will be the easy one, no point in follow this story as a comic anymore, just series of good pic without any logic behind. Good thing he still has the other stories they are developing well