Why did Maggie want her brother to go upstairs with her in The Mill on the Floss?

The Mill on the Floss was written by George Eliot in the nineteenth century. It is largely about the tribulations of a girl named Maggie and her family during Queen Victoria’s reign over England. In that era, women’s roles were confined to housework and child rearing, and virtually nobody expected a girl like Maggie to challenge that practice. The story is also about Maggie's rebelliousness against that practice. The story is essentially about a young girl who is somewhat of a rebel, wild, and a highly determined individual for the era in which she grows up. It also showcases Maggie's troubled relationship with Tom, her brother. Despite this, Maggie does admit in the story that she loves Tom very dearly. However, she often wished that Tom showed that he cared about her feelings toward him. Tom is judgmental toward Maggie. But he is nice and kind toward his mother.
I believe that in the novel, the more significant scene occurs when Tom actually wants Maggie to come upstairs with him—and not the other way around, as the question suggests. I think there may be just a mix up of the characters's names in the question. In the novel, one day, Tom excuses himself to go to his bedroom. Later that night, when Tom is finished studying, he tells Maggie to come upstairs to join him. He wants to show her a secret. He tells Maggie to cover her eyes once she joins him upstairs. When he tells her to open her eyes, Maggie is amazed.
Tom has tied a handkerchief around his head. His face is frowning. Maggie says he looks like a pirate. Tom also points his heavy sword at her. Maggie gets very scared. He accidentally drops the sword to the ground, stabbing his foot. Maggie becomes terrified, and Tom faints. After he awakes, he lays in bed to let his foot heal.
I must also comment that there is a small part of the novel in which Maggie wants her brother to come upstairs to cut her hair, because Maggie gets very upset with everyone commenting on her messed up hair. Tom does not want to do it at all, and she tries cutting it herself, which turns out to be disastrous for her hair style. Perhaps the question was referring to this part of the novel, but it seems like a less significant scene than the other scene in the story about Tom's secret that he wanted to show Maggie.