Track 4: March of the Pigs
"March of the Pigs" operates on multiple levels: in one way it represents a core aspect of the personality of Tyler Durden. There is an aggressiveness, a defiance, and yet a self-sacrificing quality to the onslaught of noise and chaos interspersed with soothing synths and pianos in this song.
This song also represents the arrival of Marla Singer in Jack's life. Jack hated Marla, but underneath the hate was a fascination -- she did, after all, appear as his power animal on the night he decided to confront her. The song contains lots of lyrics which relate quite well to the invasion of Marla on Jack's twisted hobby of emotional vampirism in support groups, including "I want a little bit, I want a piece of it, I think he's losing it, I want to watch it come down. Don't like the look of it, don't like the taste of it, don't like the smell of it, I want to watch it come down."
Finally, the arrival of Marla makes it so that Jack can no longer sleep. The old methods stop working. Once again he is set apart from the pigs, who by the end of the song "can all sleep soundly."
Track 5: Closer
So what triggers the release of Tyler Durden? In the film, directly before the montage of airports that leads to Tyler's initial introduction to Jack is a scene where Marla Singer has just exchanged numbers with Jack and asks for his name. The film cuts away before he can respond, but we can infer that he introduced himself as Tyler Durden. Until that point, Tyler had remained completely separate from Jack, but after "meeting" Tyler, Jack loses his apartment and moves in to Tyler's house.
Tyler first emerged thanks to Jack's inability to deal with his attraction to Marla, and Tyler represented the type of guy Jack imagined Marla would date... which brings us to one of Reznor's most popular songs, "Closer." This song represents Jack's feelings towards Marla, as manifested through Tyler. Although the fighting, the male bonding and the formulation of Project Mayhem are crucial to the story of Fight Club, it can't be denied that there is also a really fucked up love story being told. Remember, after all, that the film ends with Marla and Jack holding hands (while downtown crashes and burns before them).
The first verse of "Closer" represents the virginal mindset of "I-can't-believe-this-is-really-happening." The chorus boasts a lustful confidence that stands in stark contrast to the rest of the song (which is why Tyler took over in the bedroom). The line "help me get away from myself" also takes on a new meaning when compared to the love triangle in Fight Club.