The first thing Hollis notices as she is delivered to Josie's home is that "the house was falling apart." The fact that this doesn't bother her suggests she is a child jaded by the foster care system, who is ambivalent about her next caregiver.
However, she soon begins to warm to Josie, who takes her on adventures and to movies despite not having much money. Josie is forgetful, and sometimes forgets that Hollis should be in school—a fact that arguably plays a role in the growing fondness that Hollis has for Josie.
As time toes by and Josie's forgetfulness worsens, Hollis realizes that Josie cannot be let on her own, and when the "mustard woman" returns to take Hollis to a different home, she is beside herself with worry and realizes that she must protect Josie at any cost. That's why the two of them head to the Regan's summer house at Branches. Hollis's protective nature has ensured that she brings food and supplies to last her and Josie a significant length of time.
After some time at the summer house, Hollis realizes that Josie isn't really happy, and that she wants to go home. She resolves to call Beatrice and have Josie go back home, even though it will mean putting this life and the life she lived with the Regans behind her and getting used to the idea of yet another foster home. In other words, she put Josie's needs above her own.