Deadpool ends with the hero killing Ajax in the wrecked carrier and Vanessa accepting his scarred face, so the film closes on a personal win rather than a world saving one. In my opinion the key beat is Ajax admitting there is no cure, because it removes the one practical reason for the revenge. Wade cannot get his old face back, and killing Ajax changes nothing about that. Deadpool does it anyway while Colossus urges mercy, and that is where the film draws its line between the X-Men's code and this antihero.
Perhaps the cleverest use of Colossus, voiced by Stefan Kapičić, is that he stands beside the fight and still cannot talk the hero out of it. Negasonic Teenage Warhead, played by Brianna Hildebrand, fights alongside him, so the film borrows the X-Men's help without borrowing their rules. That is why it works as a spinoff rather than as a team film like x men first class, where the mutants argue about ethics for two hours and Erik Lehnsherr and Charles Xavier end up on opposite sides.
The setting of the finale matters too. The junkyard under the Pattullo Bridge in Surrey, British Columbia, hosts a decommissioned flying aircraft carrier, and the way it collapses around the fight gives the film a big set piece without a city being destroyed. Compare that with x men apocalypse, a far larger production that ends with a world threatening ancient mutant. Deadpool cost $58 million, and its climax is a rescue and a fistfight in a scrapyard. It could be argued that the smaller scale is exactly why the ending lands, since every stake is personal.
The romance carries the final emotional weight. Wade hides from Vanessa because he fears her reaction, and the ending answers that fear directly: she sees his face and the two reunite. I read this as a love story with violent set pieces more than a revenge story, and the highway opening, shot on the Georgia Street Viaduct in Vancouver, which was closed for about two weeks, promises a rampage that only gets its meaning once the flashbacks catch up.
There is also a production angle. Tim Miller made his feature directing debut here after working in visual effects, and Ryan Reynolds said, as reported by TheWrap, that the studio greenlit the film about 24 hours after he leaked the 2014 test footage. A film pushed through on that kind of fan pressure was never going to end with a tidy hero moment. Reynolds had already played Wade Wilson in x men origins wolverine (2009), so this ending also reads as a second chance for the character after that earlier appearance. Among the other R rated spinoffs, logan 2017 also lets violence carry grief, but it ends in loss, where Deadpool ends in reunion.
