Board Thread:General Discussion/@comment-26184894-20160309062153/@comment-26159109-20160309105744

Regina killed a lot of people and that potentially can be a reason why they haven't moved on yet. The only one that can help those souls is Regina since she is the one keeping them there.

Hades wants Emma in the Underworld for some reason, otherwise Neal's warning doesn't really make sense and he would've made Hook tell her to leave just like he did with Cora to Regina.

However, I don't think that was intentional and we might have this plot point unexplained just like other plot points in 5A and 3B.