Man In Black in Season 1 by Parker Thomson

Back in first season we saw the interesting episode. The episode starts with the nightmare that Claire experiences. During the nightmare we see Claire approach Locke, who is sitting down at a table reading or writing something and does not look up at Claire. She asks him what is going on, he responds with "He was your responsibility but you gave him away, Claire. Everyone pays the price now." "Him" being Aaron, many believe that Aaron is either Man In Black or Jacob, both men can be seen as harmful.

He then looks up and we see him with one black and one white eyes. This is foreshadowing the Man In Blacks appearance and his position in the present debate that he is good or bad (black or white) when we see him 5 seasons later. His attitude is very similar to the Man In Black that we all know. The fact that it is Locke in the dream with white and black eyes, then there is nothing else that the writers were trying to push us towards other than the most mysterious person on the show right now.