Authenticity
Much of Seth's admiration for Adam stems from Seth's fetishization of authenticity. Believing himself to be fraudulent in his attempts to appear edgy, Seth sees Adam as genuinely cool. While Seth runs his denim jacket through the wash to fake a battle-worn patina, Adam's leather jacket looks like it has earned its creases through years of hard use. Similarly, Adam exhales smoke through his nostrils, making cigarette-smoking look routine and unforced. By contrast, Seth holds the smoke in his mouth, afraid that if he properly inhales he might cough and reveal his inexperienced lungs. Ironically, Seth's fetishization of authenticity blinds him to the fact that Adam's cool-guy persona is just as much of a performance as Seth's. Adam only appears more authentic because he has spent more time committed to looking cool and is willing to prop up his image with compulsive lies.
Masculine Insecurity
Masculine insecurity is at the heart of the conflict in "On the Bridge." As adolescent males, both Seth's and Adam's efforts to appear like tough guys result from an impulse to hide the insecurity they feel about their masculine identities. Compensating for his small stature, Adam wishes to project an image of himself as strong, manly, and mature, lying to Seth about the fights he wins and the older girls he kisses. Seth longs to emulate Adam's rebellious and confident image, taking cues from Adam's mannerisms and dress sense. While living in the fantasy of his bravado, Adam unwittingly angers a group of grown men by flicking his cigarette on their windshield. Ironically, the men's own masculine insecurity provokes them to exact violent revenge against teenage boys by demanding that the one who threw the cigarette lick the ash off the windshield. Seth, falsely accused, refuses to give the men the satisfaction of letting their violent masculine performance triumph over his will. Seth's resistance provokes the insecure man to escalate his violence in order to save face, and he smacks Seth's head on the glass to prove his strength and dominance. In this way, Strasser depicts how masculine insecurity can set off a chain of needlessly harmful events that escalate in severity.
Dishonesty (Pathological Lying)
By the end of "On the Bridge," it is clear to Seth and the reader that Adam cultivates his cool-guy persona through dishonesty. While Seth initially believes Adam to be authentic in his claims of physical strength, rebelliousness, and confidence with older girls, Adam's overly detailed lies about why he couldn't intervene to help Seth cast Adam in a new light. The difference between how Adam behaves when faced with conflict and how he speaks of himself reveals that Adam habitually lies. While the benefit of his pathological dishonesty is unclear, Adam's lies make him something of a hero to Seth. Similarly, the confidence Adam feigns serves to obscure the real fear and insecurity that guide his actions. Ultimately, Adam's dishonesty alienates him from Seth, who can no longer trust anything Adam says. In this way, Adam's pathological lying leads him to be friendless and isolated.
Social Belonging
The need for social belonging is a central theme in "On the Bridge." From the outset, Seth's desire to be accepted by and equal to Adam is clear. Seth believes that he too can be cool if he smokes like Adam, dresses like Adam, and shows the same rebellious attitude of indifference to rules and authority. Seth's need for social belonging is so strong that he ignores his instinct to leave the bridge after Adam pretends to throw a rock at the woman in the blue sedan. Strasser writes that "[Seth] was really tempted to leave but he stayed because he liked being with Adam. It made him feel good that a cool guy like Adam let him hang around." Strasser's use of the words "let him" reveals how Seth views time spent with Adam as a privilege. However, Seth's realization that Adam habitually lies to appear cool inverts the dynamic between the boys: Knowing he can no longer trust Adam, Seth distances himself from the "cool" guy in whose company he had been so eager to belong.