Full spoilers follow.
The central deception. The film's foundational twist is established early for the audience and withheld from the boys: Drillbit Taylor is not a decorated ex-Army Ranger. He is a homeless drifter and thief who answers the classified ad specifically because three affluent-ish freshmen represent an easy mark. His "protection" plan is a pretext for access — to their money, their homes and their possessions. Every piece of tactical wisdom he dispenses is improvised nonsense, and the audience's pleasure in the first half comes from watching three desperate kids receive terrible advice with total reverence.
The escalation. Filkins, with Ronnie in tow, does not behave like a conventional movie bully; his campaign against Ryan, Wade and Emmit escalates past pranks into genuine danger, including a car chase sequence (the one during which the actors actually crashed the vehicle on set). The severity of the threat is what converts Drillbit's job from a scam into something he cannot walk away from without consequences.
The double life. To stay close to his clients, Drillbit talks his way onto campus as a substitute teacher — a second fraud stacked on the first. There he meets Lisa, a fellow teacher who falls for him. This is the film's cruelest structural irony: the version of himself that earns love is entirely fictional, and every step toward genuine intimacy deepens the lie he will have to confess.
The exposure. The con inevitably collapses. When the boys learn who Drillbit actually is — that the man they trusted was preparing to rob them — the betrayal lands harder than anything Filkins has done, because Filkins never pretended to be on their side. Lisa's discovery of the deception compounds it. Drillbit loses both the money and the two relationships the money was supposed to buy him out of needing.
The return and the ending. The resolution turns on Drillbit choosing to come back with nothing to gain. The final confrontation with Filkins is physical: Drillbit takes on the bully directly and wins, with the boys standing up for themselves as well. It is the moment critics objected to most — a film that spent its middle mocking the fantasy of fighting your way out resolves by fighting its way out — and it is also the moment the character's fabricated identity and his actual conduct finally converge. He does not become the Army Ranger; he does the thing the Army Ranger was invented to do.
What clarifies on rewatch. Once you know Drillbit is a fraud, the early scenes read differently: his confidence is a salesman's, his lessons are stalling tactics, and his interest in the boys' houses is casing. The deeper retrospective meaning is that the three boys and Drillbit are the same character at different ages — people the world has stopped looking at. The bodyguard they hire is not an outside rescuer but a grown-up version of themselves, and the film's happy ending is less about defeating a bully than about four invisible people agreeing to see each other. The 'Edmond Dantes' credit, revealed as John Hughes's pseudonym, retroactively frames the whole picture: a story about assumed identities, signed with an assumed identity.