The father-son relationships are explored in three unique ways in Henry IV, Part One. This theme is portrayed through the interactions between Henry and Hal, Henry and Hotspur, and Falstaff and Hal. Falstaff serves as a substitute father figure for Hal, introducing him to the world of commoners, the very people Hal will eventually rule. Falstaff also shares certain "skills" he has acquired, such as drinking and committing highway robbery. Critics have debated whether Hal ultimately rejects Falstaff's teachings in the same way he dismisses his own father's guidance. Some argue that Henry's lessons are crucial for Hal's future success as a ruler. Notably, some commentators stress that one of Henry's key teachings to Hal is that kingship is not merely inherited; it must be earned.

While instructing Hal on his duties as heir, Henry conveys his belief that Hotspur would be a more fitting successor than Hal. At one point, Henry even expresses a desire for Hotspur to be his son instead of Hal. Henry feels a deeper connection with Hotspur, viewing both himself and Hotspur as clear-thinking, passionate leaders. He also identifies with Hotspur because he, too, once led a rebellion against the King.

Hal's journey through Falstaff's world and his return to his father's realm has been compared to the Biblical story of the Prodigal Son, who returns home and regains his father's favor after a period of reckless living.