In the episode "Lysergic Acid Diethylamide," Walter and Peter are forced to enter the mind of Olivia in hopes of rescuing both her consciousness and that of William Bell. Much of the episode is spent in a cartoon world full of colorful craziness, but there are a couple dark and sinister moments. One such moment is when a man in a t-shirt with an X on it sabotages the zeppelin they are using. Very little is said about him until the end of the episode when Olivia very nonchalantly reveals that he is the man that will kill her.
Nothing more is ever said about it as we are left wondering what she meant by it and how she knows this. Though with the revelation from one of the Observers that Olivia is going to die, the chances are increasingly high that the X-man will make a return this season. It is also equally possible with the timeline being reset that anything from that episode might be moot and not mean a single thing...
