Right after he arrives at the cave, Robert Jordan hears about the "mujer of Pablo" from Rafael. She's big, brave, and barbarous.
Pilar comes out of the cave and gives Rafael one heck of a tongue-lashing. But she's quite friendly to Robert Jordan.
Pilar tells Robert Jordan two things: 1) Pablo is bad news; and 2) He should be careful with Maria.
Asking to see his hand, Pilar reads Robert Jordan's palm, and doesn't like what she sees.
When Robert Jordan returns from reconnaissance with Anselmo and begins a confrontation with Pablo about the bridge, Pilar announces that she supports Robert Jordan, and wants to go ahead with the bridge. The rest of the band follows her.
Pilar, Maria, and Robert Jordan have some friendly talk. Afterwards, Pilar tells Robert Jordan, when he asks, that it was the right decision on his part not to kill Pablo.
Pilar agrees to guard the explosives during the night.
In the morning, when Fernando starts to talk smack about Valencia, Pilar gets upset, and discusses the incredible time she had there with Finito, a bullfighter and former flame. In the process, she upsets Pablo.
Pilar goes with Robert Jordan and Maria to see El Sordo. She tells them on the way that she slept with Pablo last night, and that he was weeping. She also confesses that she is affected by a great sadness.
After walking a ways, Pilar wants to stop for a rest and talk. She tells Robert Jordan and Maria what happened in her town at the beginning of the war. It's a long and bloody story.
At El Sordo's, Pilar is upset by Joaquin, who seems repulsed by her ugliness. It's also clear when she talks with El Sordo that she recognizes how dangerous the mission is.
Pilar gets testy on the way back from El Sordo's. She talks about her ugliness, and admits to being jealous of Robert Jordan and Maria. She tells them to go off and enjoy each other while they have the time.
After Robert Jordan and Maria have sex in the afternoon, Pilar pries into their experience and talks about the "earth moving." Pilar notices it's going to snow, and points it out to Robert Jordan.
That night in the cave, Pilar tells a story about her former love, Finito.
After the big, tense confrontation between Robert Jordan and Pablo, Pilar announces she's all for killing Pablo, and most everyone agrees. Nothing comes of this, though.
Later still that night, Pilar talks with Robert Jordan and the others about the supernatural, and describes the "smell of death."
The next day, Pilar packs up supplies at the camp while the men are out, in preparation for the next day's escape.
During the night, as she sleeps, Pablo steals the detonators from under Pilar's nose. She wakes Robert Jordan, feeling very ashamed.
In the morning, Pablo returns with five men, and Pilar tells him, happily, that she knew he was not a total ruin.
Pilar leads most members of the band in an attack on the saw mill. They take it, losing Eladio and Fernando. She and the others come down the slope and meet with Robert Jordan
Once the bridge is blown and Pablo has returned, Pilar flees on horseback with the rest.
When Robert Jordan is wounded, Pilar and Pablo take Maria away.