We first learn of Fenichka as Nikolai and Arkady are riding back to Maryino together in Nikolai's carriage.
Nikolai admits to his son that he has taken a servant girl in to live with him. He is embarrassed, but Arkady assures him it's nothing to worry about.
A bit later, we get a glimpse of Fenichka, who sleeps irregularly because she is keeping eye on her infant Mitya (hint: who's the father?).
The next day, when Nikolai and Arkady have tea, Fenichka says she is sick. Nikolai admits that she may just be too embarrassed to come out. Arkady, in a burst of good faith, says he must go introduce himself to her. When he does, he learns he has a little brother and is thrilled.
Later, Nikolai is surprised when Fenichka appears to pour them tea. She looks ashamed, but also as if she feels she has the right to be there.
The next time we see Fenichka is when Pavel Petrovich goes to visit Mitya. She is shy with Pavel at first, but gradually becomes friendly.
She is ecstatic when she realizes that Pavel Petrovich wants to see his nephew, and whispers to Mitya that he is looking at his uncle.
Nikolai enters and Pavel promptly leaves. Fenichka confirms that Pavel came just to say hello to the infant, and wonders if she should move out of the house while Arkady is visiting. Nikolai says it is too late anyway.
Here, we learn that Nikolai met Fenichka through her mother, an inn-keeper that he took on as a servant. He was attracted to her from the start, but didn't actually become close to her until she accidentally got a spark from the stove in her eye and he had to remove it.
After her mother died of cholera, Fenichka was left alone and Nikolai took her into the house. As the narrator says, "There is no need to describe what followed..." (8.53).
Bazarov sees Fenichka later the same day, and insists on meeting her. He thinks she is very beautiful.
He quickly wins her favor when he shows interest in Mitya; the baby does not protest when he holds him.
Fenichka later goes to Bazarov for help when Mitya cries in the night. He stays up with the infant for several hours.
We get a glimpse of Fenichka and Nikolai's relationship when Nikolai is thinking of his wife and Fenichka enters. He is frustrated that she interrupted his fantasy and dismisses her in the manner of a typical serf-owner.
When Arkady and Bazarov return later in the novel, Arkady quickly leaves for Nikolskoye, leaving Bazarov alone. The one person he keeps in close contact with is Fenichka.
Fenichka likes Bazarov and feels she can be more open with him than she can be with Nikolai. Bazarov begins to become attracted to her and thinks that she becomes prettier everyday.
One morning, Bazarov comes to visit Fenichka in an arbour (cluster or trees). He flirts with her while she prepares a bouquet of flowers for breakfast.
She thinks he is silly and admits to him that Pavel Petrovich scares her. Fenichka does not pick up on how forward Bazarov is being with her.
When he asks her to smell a flower with him, he kisses her and she is astonished.
A moment later Pavel Petrovich appears from behind a bush. It is clear he has been spying on them, and Fenichka is angry at Bazarov for getting her into trouble.
Pavel Petrovich waits until the next morning to challenge Bazarov to a duel. Bazarov assumes he must be in love with Fenichka. It does not occur to him that he is doing it for his brother's sake.
After the duel, Pavel Petrovich calls on Fenichka. He questions her love for Nikolai, and she says (all too literally), "If I did not love Nikolai Petrovich I would have nothing to live for" (24.147).
Pavel begs her to love his brother with all her heart. He forgives her for what happened with Bazarov and squeezes her hand.
The next time Pavel talks to Nikolai he begs him to carry out one request, "Marry Fenichka... She loves you: she is the mother of your son" (24.178). Nikolai is thrilled.
At the end of the novel, Nikolai and Fenichka are married. Fenichka and Katya get along very well and raise their two sons together.