Fangirl, Vol. 4 primarily focuses on Cath's journey through personal growth and self-discovery as she navigates the challenges of her freshman year, including her academic responsibilities, relationships, and passion for writing.

Family dynamics are a significant aspect of 'Fangirl, Vol. 4'. Cath's relationship with her twin sister Wren, who is acting increasingly reckless, and an unexpected reunion with their mother add emotional depth to the story, exploring the impact of family on one's identity and the struggles of maintaining familial bonds.

In 'Fangirl, Vol. 4', Cath faces the challenge of balancing her dedication to her fanfiction and the looming release of the final Simon Snow novel with her real-life responsibilities, including her relationship with Levi and her academic performance. This tension highlights the difficulty of prioritizing one's passions while managing everyday demands.