What does Lyddie do to help out Brigid?

Lyddie does a lot to help Brigid during the events of this story. I would say that the first thing that Lyddie does is help Brigid learn how to work a loom and operate in the factory. Lyddie is definitely not happy about doing this. Lyddie sees Brigid as an obstacle that prevents her from working at her full capacity; therefore, Lyddie can't earn as much money. This is a moment in the text when readers are steered toward having a negative reaction to Lyddie and her decisions. Somebody had to teach her how to do the work, and they graciously taught Lyddie the ropes. It's painful to see Lyddie not pay it forward. Eventually, Lyddie does begin to help Brigid out without being forced to do it. Lyddie will teach Brigid how to read and even physically protect Brigid from Mr. Marsden's sexual advances. By far my favorite Lyddie to Brigid assist can be found late in the book. Lyddie has been fired from the factory job, and she decides to confront Mr. Marsden. Before doing that, Lyddie writes up two identical letters. The letters are written to Mrs. Marsden and they explain everything that happened in the weaving room. Lyddie gives one letter to Brigid and tells Brigid to mail the letter if Mr. Marsden ever steps out of line again. Lyddie then confronts Mr. Marsden and hands him the other copy.

"Good night, Mr. Marsden. I hope you sleep easy—before you die."

Initially, Lyddie's not exactly thrilled to be working alongside Brigid. The young lady is a Catholic, and Lyddie shares the common prejudice of most Americans at that time against "Papists." Also, Lyddie feels that being forced to train a newbie will slow her down, which will mean less money.
However, as time goes by, Lyddie starts to feel protective towards Brigid, showing her the ropes and generally looking out for her. The two become firm friends, and soon there's nothing that Lyddie won't do to help her new pal. She helps Brigid learn how to read, just as she herself was once taught. Lyddie also sacrifices her own job by protecting Brigid from Marsden's unwanted advances. But before she leaves the factory, Lyddie, ever the rugged individualist, gives Brigid the means of standing up for herself. She gives her a letter to be sent to Marsden's wife if her husband tries again in future.