The mermaid princesses were carried away. Their fate was to become Meredith's playthings. Perhaps when he got tired of them, he would give them to his subordinates.
This was very common in the Ossaide Dimension. Although civilization had developed to a high level, this society did not even care about the lives of the lower-class residents, let alone protecting the human rights of the indigenous creatures of the other dimension.
It was not illegal to treat intelligent creatures as ingredients in the Ossaide Plane.
The reason why the Azure Planet's people did not have the same miserable state as the mermaid princess was because they were in the Southern Continent.
On the one hand, it was because the humans and Ossaids were very similar in appearance. On the other hand, it was also because there was nothing special about the flesh and blood of the humans.