We didn’t know and didn’t hear a word about this family up to the end of the novel. They appear right before the ending. What do we know about them? Well, nothing much, but no matter what, this family deserves our attention as well.
They were the migrant family who was looking for some work in California. In the book, they were sharing the boxcar with the Joads on the ranch where they all pick cotton. Like the Wilsons, their union with the Joads underscores the novel's theme of human unity. Moreover, they show how important it is to be together in hard times that in any situation friendship and back up will help to survive.
During the heavy rains, Mrs. Wainwright helps Ma deliver Rose of Sharon's dead baby. Also, Mr. Wainwright helps Pa to build the dike that will save them from the flood. After the force to leave their homeland, the whole Joads family understood and studied that it is normal to accept help as well as it is cool to give it. After some time, when two families start having suspicions about relationships between Al and Agnes, Al made a proposal on which Agnes answered “Yes.” After Al became engaged with Agnes (Wainwright's daughter), they were crying from happiness and even removed the wall between two families, making a symbolic one big family without boundaries. We can say for sure that the Wainwrights family is the one which brings kindness and shines to the book.
Mr. and Mrs. Wainwright in the Essays