I'm just gonna go for it here, draw a (story)line from "Across The Sea" to "The Candidate." I'll throw in everything I can that seems to fit, but will try not to get too specific, cuz I always get bogged in details, story cul-de-sacs, y'know? and I'll name only a few characters, and paint the broad strokes of what's come before and what's yet to come...
Here we go.
A ridiculously long time ago, Jacob and Esau are born on the Island to Claudia, who survived the wreck of a ship from Atlantis. Crazy Mother, the Protector of the Island at the time, who is also a smoke monster, kills Claudia and raises the brothers as her own.
The ghost of Claudia appears to Esau and tells him where he comes from, beyond the sea. He's always been restless and once he hears this truth, he learns why—he wants to go where he belongs, his home, beyond the sea, among other people.
This drives Esau to leave Momster and Jacob and join the other people on the Island.
Jacob becomes Momster's successor, the Protector of the Island.
To punish Esau for killing their Momster, Jacob unwittingly turns his brother into a new smoke monster.
Both are subject to Rules created by the Momster as Protector and possibly the Protectors before her, ostensibly all designed to protect the Island and its Heart.
Some of these Rules...
Esau cannot leave the Island (unless there is no other life on the Island).
Jacob and Esau cannot kill one another.
Esau cannot harm those Jacob protects, Jacob's people, aka the Others.
Esau cannot harm those who have been touched by Jacob, some of whom are Candidates for Protector.
Jacob can be killed by one of his people who sincerely desires it.
Jacob is content to carry out his duties as Protector of the Island, but at the same time, entertains a growing anthropological hobby on the side: choosing and bringing outsiders to the Island to see if and how they can live with the gifts that it offers.
Esau considers the Island to be his prison. He still wants what he wanted before he was monstered up—to go home. One of his gifts is an understanding of how things work. With this, he's learned that killing all life on the Island will effectively "tilt the game," with the likely result of shorting out the Rules, freeing him from the Island, possibly destroying the snowglobe, and maybe freeing a great evil that quietly waits, expressing itself in the form of Infection.
Events orchestrated by Jacob lead to the time travelling misadventures of some of our Losties and the Incident in 1977. The Incident creates the divergent reality of LOST2. From that moment on, there are two versions of every person, place, and thing, each living their slightly different lives in either LOST1 or LOST2. Two versions of everything except for the Island's Heart and those directly connected to it, Jacob and Esau.
Meanwhile, single-minded Esau sets in motion events that lead to the execution of his loophole—the murder of brother Jacob by Other Ben. So sad, because all the while, Jacob's been trying to grant Esau his smoking heart's desire, to get him off the Island and home. Well, *A* home—LOST2.
Esau doesn't believe that there is an embodiment of evil imprisoned with them in the snowglobe. What he does believe in is the petty evils of mankind, the weaknesses and flaws of human nature, which are universal. So, he barrels on in pursuit of his emancipation, not thinking twice about how his prison break would leave an escape route for this nonexistent capital-E evil.
Jacob knows better—or at least, he believes better—that there IS a slumbering evil, waiting patiently for release, and it manifests itself on the Island thru Infection. In any case, Jacob comes to the realization that he cannot kill Esau and he cannot let him succeed in leaving the Island the way he plans to, so he arranges for Esau to leave without creating an escape tunnel.
Jacob has seen Esau's loophole play coming and brought to the Island a number of Candidates, groomed over years and possibly even generations. Candidates who can take his place as Protector once he's gone. Esau sees their arrival as Jacob's contingency plan, a threat to his escape, essentially, obstacles to be overcome, removed, killed. Jacob anticipates Esau's conflict with his Candidates, their companions, and Island deputies and in fact, counts on them.
It will be through their confrontations that Esau will end up visiting the Heart once again. Remember, the energies of the Heart do not kill, but they do transform. When Desmond, who has proven himself essentially impervious to massive EM radiation, forces Locke-ness into the energies of the Heart, Esau's consciousness, perhaps with a boost or redirection from Desmond's own absorbed energies, will be blasted out of Locke-ness's body in LOST1 2007, and into the cells of Claire's unborn child in LOST2 2004.
This will leave behind an empty vessel, Locke-ness's form, which, thanks to the decayed body of Momster in the cave, we know to be indistinguishable from the original, and so, a perfect fit for a John Locke-shaped Whispering ghost sulking about on the Island.
Maybe in time ghost Jacob will have the Lighthouse rebuilt, so that he can visit it, use the mirros to watch his brother grow up and live his life in LOST2. Maybe on one of those visits, he will see Esau-Aaron looking back at him, smiling.
This is the HAPPY HAPPY ENDING.
The NOT-SO-HAPPY HAPPY ENDING involves Infection completely overtaking Esau, pushing him from resentful and pissed-off to evil. This Esau is released into LOST2 as baby Aaron. Then, thru the concerted effort of the enlightened LOST2 815ers and the Islander Illuminati (Chang, Eloise, Widmore, maybe Richard?), collapsing the reality of LOST2 so that Esau-Aaron is born into a world that is moments from deletion. The collapse reboots (and/or restores) reality from 1977 on to LOST1, preserving the lives, loves, and histories of the Losties on the Island.
A few things this story does not explain or involve...
The deal with Ghost Jacob, who's visible only to Esau and the Candidates.
A crisis in LOST2. Would the focus of it be Aaron's birth in LOST2? Doesn't seem like reason enough for all of the LOST2 815ers to get their LOST1 memories downloaded. I think that Locke2 will have to step up to accept his Locke1 life and somehow engage Esau across realities, within Locke-ness's body.
The identity of the new Protector. I could see it being Jack, Desmond, or a refreshed John Locke. With Ghost Jacob stomping about the jungle right now, I think he might have an Aslan-on-the-Stone-Table chance at a comeback shot at the title, too.
What Kate will do, cuz as a Kandidate, I know she WILL do Something Important.
Keep on keepin on~