How is the woman who arrives on this particular evening different from most of the sitting parents?

In the short story "Winter Night" by author Kay Boyle, the mysterious brunette sitter shows affection and warmth toward Felicia, the daughter of wealthy parents and whose mother is always absent in the evening. Felicia's father has been abroad fighting in the war for much of Felicia's life, so she does not have any substantial memories of him or with him.
The rotation of maids and sitters who have watched over Felicia in the past performed their job mechanically; they showed no emotional attachment or warmth towards Felicia. In fact, they performed their duties in a robotic manner so that they could quickly get Felicia to bed.
Felicia was treated as just another task. However, the new sitter takes her time to get to know Felicia, and tells her stories about a girl she once knew of whom Felicia reminded her. She even helps Felicia clear up the dinner table so that they can spend some time together sooner.
In the end, Felicia falls asleep in the sitter's arms. When the mother comes home and sees them sleeping, the mother is shocked because the other sitters never showed such closeness towards her young daughter.