Okay so this is all very fresh in my mind and still may have some holes but here it is: I think the candidates can CREATE whatever they WILL on the island. This is the magic box that Ben spoke about to Locke in seasons back (but I'll get to that later). In tonight's episode "The Lighthouse" Jack asked, "Why have we never seen this before" when speaking of the Lighthouse. Hurley answered "Maybe because we have never looked for it."
Could the candidates have to power to create before them whatever they will to happen? Here are a few quick examples I have thought about:
Locke's Dad: Ben told Locke that he brought him to the island. Because he willed it (Although I'm not sure if Locke or Sawyer actually brought him)
Locke's knives: In the ALT timeline they were never on the plane. Could it be that they were NEVER on the plane but Locke willed them to the island?
Charlie: He died in season 1 but Jacked WILLED him back to life.
Jack's dad: Maybe he was never on the plane at all (like in the ALT timeline) but he WILLED him to the island.
Jack in "What Kate Does" told the guards to move away and they did
Hurley in "The Light House" told Dogen he was a candidate and he had to listen to him.
So these are just a few theories. I think the candidates are channeling the same kind of will/fate powers that Jacob has. Jacob willed them to come to island and they did. And it kind of puts a new twist to the close-ups of the LOSTies eyes in the beginnings of episodes... Of course there are many holes in this theory but I just had to put it in writing and throw it out there.
The Will of the Candidates = The Magic Box