In chapter 21, page 182 of Chains, Isabel said she felt “chained between two nations.” What did she mean?

Chains was written by Laurie Halse Anderson. It is a young adult novel that was published in 2008. The story is about the experiences of slaves, the Loyalists, and the Rebels during the years leading up to the Revolutionary War. Isabel is a main character in the novel. She is a thirteen-year-old slave who works for the Locktons, a Loyalist family in Manhattan. Isabel's previous owner, Miss Mary Finch, had promised to grant freedom to Isabel before her death.
Isabel was an educated slave who could read and write. She strongly desired to be free throughout the story. We learn about the deep thoughts in Isabel's mind regarding her slavery. Isabel feels she cannot escape her slavery simply due to the fact that she was sold to Loyalists after Miss Mary Finch died. She wishes she could change her circumstances.
One day, Isabel is fortunate to be able to strike up a conversation with Captain Campbell, who is one of the Rebels. She confesses her desire to be free, and he is sympathetic toward her. He asks about her owners, and she admits that they are Loyalists. Once he hears this, he tells her that he does not keep slaves, but he cannot help her. He refuses to interfere with Loyalist property, referring to slaves owned by Loyalists.
Isabel eventually accepts the reality that she has no way to claim her freedom. As she ponders why she can't escape her slavery, she realizes that the reason why she has no escape from slavery is simply because she was purchased by Loyalists. Therefore Isabel feels like she is chained between two nations, namely the nations of the Loyalists and the Rebels. The Loyalists would like to continue her slavery, and the Rebels refuse to interfere with the Loyalists' property, even though some Rebels may be sympathetic toward her plight.