4. Cortexiphan
Between 1981 and 1983 Walter and Bell carried out the Cortexiphan trials, a drug that was (as explained by Nina) designed to prevent brain shrinkage, allowing far greater brain functionality in adulthood if administered during childhood. The idea was that this extra power would unlock unique abilities in certain people, something weve seen to a devastating extent during the show (usually by people unable to control their ability) and also as the source of Olivias special edge. We know that, as a result of Walters initial tear of the Universe by rescuing Peter, the main reason the Cortexiphan children were further experimented on was because of their potential for traversing Universes. This doesnt, however, necessarily mean that this is why they were initially created. Although Bells endgame with the ZFT manifesto relied on Cortexiphan to collapse the Universe, they may still have a further role to play. Walter has only ever suggested the experiments were done to prepare for something in the future, but it was never confirmed that this was to do with the other Universe. In fact, very few of the Cortexiphan children have been used so far so they may have one more play to make before things are over.
The Questions: Why was Olivia chosen for Cortexiphan? What was the original plan for the children? Has the Cortexiphan really left Olivia, or does she still have powers? Are the Cortexiphahn subjects needed to either help defeat the Observers, or to restore the timelines after they are gone?