While it is true that Reuben Land, the young narrator in Leif Enger's Peace Like a River, undergoes a change in his thinking about Roxanna Cawley, she seems to love and accept the Land family just as they are right from the beginning.

When Jeremiah Land and his two youngest children, Reuben and Swede, pull up (with their Airstream trailer) to an isolated farmhouse with two gas pumps and sign that says Dale's Oil Company, they do not expect to find Roxanna.

Land asks her if he can buy some gas, something others have not been willing to do since it is Sunday. Reuben says: 

At this moment a better observer than me would've seen some acquiescence in the woman's eyes, some raising of the gate. I saw nothing of the kind, but Dad must have, for when she abruptly shut the door he stayed right where he was.

Roxanna and Swede immediately enjoy one another's quirky sense of humor, and as the Lands get ready to search for a motel for the night, Roxanna offers to let them stay at her house. That night, Reuben has a breathing episode, and Roxanna joins Land in getting him through it. As she leaves Reuben for the night, she leans down and kisses him on the cheek.

We learn that Roxanna has had some difficult things happen in her life, but she is a survivor; she has had plenty of reasons not to trust, yet she instinctively trusts Jeremiah Land, a godly man, and his family.

From the beginning, Roxanna seems to recognize some kind of kinship with the Land family, and it grows stronger and more mature over the next months. Not too much later, when Land unexpectedly loses his life, Roxanna becomes the head of the Land family. She just seems to be "one of them" from the first time they met her.