We don't see any signs of Miriam having an incest fetish until after her time in the dreamscape and her post-dream crystal session with Adrian.
There is just the proviso that she did not freak out in the least when she woke up. And that could still mean Dani and/or Erin did it when they were "preparing" her for Adrian. But he
was fine with it too.
I'm still inclined to think that Dani used the crystal on Erin on Einfríður night, and then they used it on Miriam. So I'm still not sure who's actually running things at the moment. I don't know why I think that, I just do.