Marla Singer (Helena Bonham Carter)’s Timeline and Summary

Marla walks into a cancer support group puffing on a cigarette.
When our narrator confronts her as a "tourist" she agrees to split the support groups on different nights.
However, she calls our narrator after she attempts suicide, but Tyler shows up.
She starts sleeping with Tyler, a lot. And loudly. In the mornings, our narrator is mean to her.
Once a bunch of bald men start sleeping in Tyler's house, Marla can't take it anymore and she stops coming over.
However, one day the narrator calls her and asks what his real name is. She tells him his name is Tyler. This is the first he knows of this.
Worried that Project Mayhem will harm Marla now that she knows his true identity, the narrator gives her money and tells her to run away.
She does, but members of Project Mayhem capture her and bring her to the narrator, just as he's blown a hole in the side of his face.
Marla tends to him as buildings around them explode and fall.