The first we hear of Katya is that she and Anna Sergeyevna were orphaned when both of their parents died.
Later, when Anna Sergeyevna's husband died, the two of them went to Germany for awhile, but then got homesick and returned to Nikolskoye.
When Bazarov and Arkady go to Nikolskoye, Anna Sergeyevna introduces them to her younger sister, who is shy and constantly blushes before them.
Katya mainly stays in the background until Bazarov goes to play cards with Anna Sergeyevna and the neighbors. Anna Sergeyevna requests that Katya play something for Arkady.
Katya plays Mozart's Sonata Fantasia in C minor. She is a bit stiff, but as she goes on she begins to put some emotion into it.
Though Arkady admires the piece, he thinks it has more to do with Mozart than Katya. When he tries to discus it with her, she becomes withdrawn and goes back to working on her flowers.
Though Bazarov seems to be getting close with Anna Sergeyevna, Arkady is confused when Bazarov tells him that he prefers Katya.
As Bazarov and Anna Sergeyevna begin to spend more and more time together, Arkady settles for Katya. She understands what is going on, but the two of them become friends and realize that they have much in common.
When Bazarov and Anna Sergeyevna begin to have late night discussions, Katya will stay up playing for Arkady.
When things go bad between Bazarov and Anna Sergeyevna, and Bazarov and Arkady resolve to leave, Arkady mutters into his pillow that he will miss Katya.
When the two of them make a brief stop at Nikolskoye before going back to Maryino, Katya stays in her room and doesn't even come down.
Yet, when Arkady circles back alone to Nikolskoye, he sees Katya in the yard. She blushes and is thrilled to see him. He suddenly realizes why he has come to Nikolskoye.
Arkady begins to take Katya for walks in the garden.
One day, she tells him that she thinks he is beginning to come out from under Bazarov's influence. She says the same thing is happening to her sister.
Katya admits that she never liked Bazarov and says that she had nothing in common with him.
She says, "He's a wild beast, while you and I are domestic animals" (25.20).
Arkady kids Katya that she is a bit afraid of her sister. Katya explains to Arkady that her sister is becoming much fonder of him, though she is coy about telling him why.
Arkady thinks that Katya keeps everyone at a distance. He wonders if it is because of her wealth. She protests that all the wealth is her sister's. Arkady thinks that she is a bit proud of her poverty.
Katya admits that she would not marry a rich man because she doesn't like the idea of "a mere subordinate existence" (25.67).
In comparing Katya to her sister, Arkady accidentally gives voice to his extreme admiration for Katya. He becomes embarrassed and walks away.
When Anna Sergeyevna finds her sister a few minutes later, she tells her to take better care of her feet.
Katya thinks "Pretty little feet, you say... Well, before long he shall be kneeling at them" (25.93).
She immediately feels ashamed of the thought.
The very next day, Arkady takes Katya out to the portico. Anna Sergeyevna has warned her not to take so many private walks with Arkady, but Katya tells herself that this is the last one.
Arkady tells her that she is the sole reason he is beginning to come out from under Bazarov's influence. He tries to get out his proposal, but he begins stammering.
The two of them suddenly stop when they overhear Bazarov and Anna Sergeyevna discussing their feelings for one another. Anna Sergeyevna admits that she is becoming interested in Arkady.
As soon as they move one, Arkady tells Katya that he is in love with her and asks her to marry him. After a long pause she says yes. Arkady is thrilled and Katya begins to cry joyful tears.
Anna Sergeyevna is surprised, but grants her approval. Bazarov tells Arkady that Katya will make him very happy, though he seems to mean it as a slight.
As soon as Bazarov leaves, Arkady stays up talking with Katya and quickly forgets about his former mentor.
When Anna Sergeyevna asks them if love is an imaginary feeling, they don't know what she is talking about.
The novel ends with Arkady's marriage to Katya. Anna Sergeyevna leaves them a generous endowment.
At the farewell party for Pavel Petrovich, Katya whispers into Arkady that they should toast to Bazarov's memory. They squeeze hands.
Katya and Arkady have a son, which they name little Nikolai, and Katya and Fenichka become close friends as they raise their children together.