What significant challenge does Denny face in his life?

Denny faces significant challenges throughout his life, particularly centered around the custody battles for his daughter, Zoe. This struggle is particularly impactful as it not only tests his emotional resilience but also affects his relationships and sense of stability. The custody battles illustrate the complications and stakes involved in Denny's personal life, showcasing themes of parental love and the fight for family during adversity. This storyline also serves to deepen the reader’s connection to Denny as a character, emphasizing his commitment to being a good father despite the challenges he faces.

While Denny does encounter elements of financial struggles, job insecurities, and health issues at different points in the narrative, the custody battle with his estranged wife stands out as a pivotal and ongoing challenge that shapes the course of his life and the decisions he makes.