Mr. Darling and Peter Pan are foil characters, which means that they have diametrically opposite tendencies, habits, and beliefs. Mr. Darling is fussy, exacting, responsible, and above all, practical. He keeps a sharp focus on his family and his finances. He also has "a passion for being exactly like his neighbors." In Chapter 1, the narrator describes his concern about what others think of him:
No nursery could possibly have been conducted more correctly, and Mr. Darling knew it, yet he sometimes wondered uneasily whether the neighbours talked. He had his position in the city to consider.
Here, the narrator claims that no nursery could be "conducted more correctly" than the Darling nursery. The formal diction of this passage reflects Mr. Darling's stringent attitude toward family life. Everything must be "just so," and despite his exacting standards, he still "wondered uneasily" about the neighbors' opinions. He thinks often of the opinions of others and the impact that they might have on his position in the city. In many ways, he lives vicariously through other people, as he constantly seeks approval and lives by the admiration of his wife and the approval of his neighbors.
By contrast, Peter Pan is magical, immortal, youthful, and (quite literally) flighty. He has no fear and no desire for safety. Nor does he worry about the opinions of others. This is perhaps the greatest difference between Mr. Darling and Peter—the former lives for security and external validation, and the latter lives for freedom and wild adventures. Peter lacks any moral objectives—and yet has "good form"—which prompts Captain Hook to realize that "Peter did not know in the least who or what he was, which is the very pinnacle of good form." Whereas Mr. Darling constantly monitors his own behavior, Peter has no idea who or what he is. Age and aging prove to divide the two characters; Mr. Darling continues to age into his thirties and forties, whereas Peter remains immortally youthful.
Two interesting similarities between the characters are, first, their arrogant attitudes and, second, the fact that they both play a fatherly role in the novel. The first chapter introduces Mr. Darling as a traditional father and breadwinner; later in the story, Peter Pan earns the title "father," which corresponds to Wendy's title of "mother" of the Lost Boys. Both Mr. Darling and Peter believe that their ways of life are the best, and their motherly counterparts always agree with their opinions and decisions. Ultimately, though, their fatherly roles only bring their differences into further relief and confirm that they are foils for one another.