August is an Observer. He is one of the twelve science team members sent to study humanity before the creation of the Observers and learn more about their evolution as a species. The work August and his fellow scientists were doing would be used to plan a full-scale invasion of the past, although this was unknown to him or any of his team members.
August was exiting a movie theater in the Alternate Universe with December when the two were approached by September, who explained the critical deviation of accidentally distracting Walternate who was in the process of curing Peter Bishop. August told September that he had made a grave error, but he foresaw an opportunity to rectify this mistake.
August had been following Christine Hollis since 1989 when he saved her from an earthquake in San Francisco. He interfered in her life once again when he held her hostage so she wouldn't get on a plane and die when it crashed. He began developing feelings of love for her. These feelings were unknown to the Observers, but many of them began experiencing emotion due to their proximity to emotional human beings.
August is shot and dies after refusing to take corrective action that would result in Christine's death. He is driven away by September during his final moments. In tears, he states that he loves Hollis, which September replies "She is safe as you made her important - she is responsible for the death of one of us". ("August")