I can like stories with 'pets' if they are done right - it's usually a single pet / master or a few, like say orin, oku, chen type pet situations - they could clearly leave their masters if they hated it..
Or a really good one - http://dynasty-scans.com/chapters/invasion_nue_girl :)
Even though Nue isn't a voluntary pet it's clear by the end of the sequel they both kinda like the set up and I could see really enjoying a 3rd one where Nue agreed to become a pet, and had the lead and bracelet removed and lived at the shrine - and Remiu realising she really liked to care for and be nice to her etc.
It's not really a rational reason why I can be ok with some pet set ups and not others - I think it's when it's more like a world wide institutionalized thing and much more like slavery, even 'breeding' them and them being 'sold' etc and they don't seem to have rights or any say in their situation - then it just seems totally unacceptable.
last edited at Oct 5, 2016 6:16PM