The Eagle is a 2011 film based upon the Rosemary Sutcliff historical novel The Eagle of the Ninth.A young Roman soldier named Marcus Flavius Aquila goes on a quest to find the eagle standard of his father. It is loosely based on the mystery of the real Roman Ninth Legion, which disappears from the historical record after having last been mentioned as present in Scotland in the early 2nd century.
An Aesop: Honor Before Reason is both good and bad, as it's the reason why Esca and Marcus survive through the film, but the things done in the name of avenging honor are shown to be violent and possibly ultimately pointless.
Bait and Switch: When he recovers the Eagle, Marcus engages a masked figure who'd earlier been displaying the Eagle. The man wears the ring of Marcus's father, and Marcus has discovered that some Romans have turned British. He rips off the mask...and sees it's just the Seal King. To finally settle the matter, the Seal King responds to Marcus' demands saying that he took the ring after killing his father, who implored for his life like a coward (he does so in his own language, which Marcus does not understand, and Esca gives a false translation to not hurt his companion).
Chekhov's Boomerang: The chin-strap scar. First crops up in a blink-and-you'll-miss-it shot, then is repeatedly used as an identifying mark for Roman legionaries.
Darker and Edgier: Than the original novel. The film ups the amount of actual fighting considerably from the original novel, nor was there any infanticide originally.
Does This Remind You of Anything?: Tribal warriors with war-paint and suspiciously Mohawk-ish haircuts chasing after someone from another tribe and someone from The Empire across miles and miles of unspoilt wilderness: Last of the Mohicans much?
Executive Meddling: The film originally ended more ambiguously, with Esca and Marcus riding into the mists. But this played so badly with test audiences that they hurridely shot a newer, definitive ending with Esca and Marcus delivering the Eagle and riding off into the sunset. The rushed nature of the newer ending shows, badly.
There is also an alternative ending where Marcus ends up burning the Eagle on Guern's funeral pyre because he believes it rightfully belongs to the brave men who died fighting for it. The final scene shows him and Esca walking back to Hadrian's Wall, discussing possible plans for the future like starting a farm in Spain to breed horses.
Marcus undertakes the very dangerous hunt for the eponymous Eagle in hostile territory assisted only by a slave who has a fairly strong incentive to murder him and take off, all in the name of his family's honor.
Esca, the slave in question, has no particular incentive not to simply kill Marcus and leave; the only reason he doesn't, despite ample opportunities to do so, is because he gave his word.
Not So Different: The Roman and the Britons; both are quite capable of barbarism and nobility towards themselves and others, both have a thriving slave trade, both factions have some kind of evil aristocrat (Seal King and Placidius), and both 'worship' the Eagle as a symbol of their people and their military prowess. Marcus and the Seal Prince, his Shadow Archetype, have a more personal one: they both treat their peers politely, but have a disdain for slaves, they both set out to avenge the loss of the Eagle (just a hunk of metal) as well as the deaths of their fathers, and when both Kick the Dog, they display some humanity in spite of it (Marcus performing it like a mercy kill, the Prince laying his victim down with dignity.) This is symbolized by the fact that, the Prince, who spends most of the movie with war-paint, has it washed off in the end, at which point he kind of resembles Marcus. Also, the music playing when the Druid beheads one of the patrol is the same as when Esca is forced to fight in the arena. The song is called 'Barbarians'.
Shoot the Dog: Or "kill the boy." Notable in that the primary protagonist and the primary antagonist both do this.
The chief difference is this, though: When Marcus goes to slit the Rogue Warrior boy's throat, even he, after lecturing Esca, hesitates before eventually going through with it. There was also the risk of the boy running off and coming back with reinforcements, so there was a sense of pragmatism. When the Seal Prince shoots his dog, he's not only doing it for really no reason at all, but he's slitting the throat of his own son!