In Rainbow Rowell's "Fangirl," Cath, a dedicated fan of the fictional Simon Snow series, navigates her first year of college while struggling with her introverted nature, her twin sister Wren's distancing, and the pressures of adulthood. She grapples with her love for fanfiction, especially her popular "Carry On, Simon" series, and the challenges of finding her own voice and identity outside of the fictional world. The novel explores themes of family, identity, love, and the power of fandom.