The girl’s name is Fern Arable. She was played by Dakota Fanning in the live-action release of the movie based off the book in 2006, and in the 1973 version, was voiced by Pamelyn Ferdin. Fern adopts Wilbur the pig when Wilbur is a small piglet. She only gets to visit him occasionally in the book. However, the book has a happy ending. For those who wish to remain in the dark about the book’s plot, stop here.
SPOILER ALERT. Joan is the only human character in the book that seems to be able to understand the animal characters. She helps the barn animals prevent Wilbur’s slaughter despite how much her father wants to put him in the slaughter house.