New theory about Ariel that I just found which could also be possible when you think about it.
We’re all expecting her to be in Neverland or possibly Storybrooke after that teaser. But what if she’s actually in the EF? What if she is the one who pulled Neal to shore to save him drowning like she did to Prince Eric in the movie. Once she saw MAP coming, she ran away.
It would also make sense if she is in FTL to tie in with what Regina said in ‘Skin Deep’ about her mermaid problem and Rumple’s story about the Ink.