One thing that has constantly bugged me throughout the whole of Lost has been the mystery surrounding Walt and Aaron. Darlton say they have planned all along for Walts story, so we can probably expect to see him in series 6, but what about Aaron? Here are my thoughts...
In the earlier series, so much emphasis was placed on him as a "special child". For starters, he broke the tradition of dying during childbirth, and both he and his mother survived.
Then later on, there was the "Aaron is where he is supposed to be" line from Christian. I think it is entirely possible that this was Nemesis in Christians form, telling Claire the wrong information, that Aaron should be off the island. If it was Nemesis forcing Aaron off the island, then doesn't this mean Aaron is in fact not where he is supposed to be, and Aaron should really be on the island, where he belongs?
It is interesting that if we take Nemesis as being able to pose as Christian, then it was Nemesis who "tricked" both Locke and Aaron into leaving the island, under the guise of promises and wisdom.
Could it be that Locke and Aaron are both special, and some evil force is manipulating them into leaving the Island, when in actual fact, the 'special ones' should be on the island? Note that Walt, through happenstance also ended up leaving the island.
These events have further connotations. If my above statement is true, that Aaron should really be on the island, then why should he be? Could it be that Aaron eventually grows into Jacob, which is why he is deemed so special? Could it be that Aaron, Walt, and Locke are all special, yet evil is currently winning, forcing them all off the island. Or are they simply not special at all, and have no relevance?
I find the theory that Walt/Aaron?locke are simply not special as a bit too much of a cop out. From a technical point of view, why would so much time be spent portraying to the audience how special Aaron and Walt are, if they don't have any significance?
I believe they are special, and we will find out why in Season 6.