Board Thread:Spoilers!/@comment-26160044-20151209220321/@comment-32390199-20151211083926

I'm bored so I'm just going to list who is in has potential to appear with their reasons for being in the Underworld.

Who I think are not going to appear
 * Cora: never told Regina she loves her with her heart in the right place, and probably sticks around until she knows Regina returns home safe and then moves on.
 * Henry Sr.: probably something with Regina, finding out if she has found happiness and forgives her for killing him, and is glad she has done it now that she has found happiness.
 * Peter Pan: trying to be the father that he never could be for Rumple.
 * Milah & Bealfire: regretting to not have been there to see Bae grow up which explains why Bae is a child. That way we can also avoid Emma's feeling for Neal as he will stay a kid.
 * Blind Witch: she either is a Cruella case in terms of, she is pure evil, or we get a revelation.
 * Cruella de Vil: never got to kill the Author, and probably won't move on.
 * Liam Jones: probably wanted to know what has become of Hook.
 * Graham: never got to say Emma he loves her. (would actually be funny to see Graham, Neal and Walsh (even tho that wasn't real love) talk to Emma before she revives Hook).
 * Fairy Godmother: never got to complete her task of looking out for Cinderella
 * Prince James: wants to know who his brother is and probably blame him for having a good life or something, or just talk about how it could've been.
 * King Leopold: kinda iffy on this one, but I think he still wanted to say goodbye to Snow.
 * Daniel: Regina's happiness (may have come to terms with it after 2x05 if he realized what Regina said)
 * Jack: died in an unjustified way (in her point of view)
 * Maid Marian: cheated out of life and probably will give green light for the dull Outlaw Queen.
 * Percival: never got revenge on Regina

The others are not important enough to even make a return imo
 * Eva: died in the presence of her daughter
 * Ruth: saw her son with his happy ending
 * Greg & Tamara: probably moved on when they met in the Underworld
 * Ingrid: came to terms with her fate and told everything she wanted before she passed on
 * Apprentice: lived long enough and told what had to be told