Accuracy in comic book adaptations is a serious question, and adaptations have had to deal with it since George Reeves and Adam West. It often means finding places with room to wiggle. Departing from canon has the potential to help the characters grow and expand but also runs the risk of diluting what makes them special in the first place. Michelle Pfeiffer's Catwoman, for example, is beloved despite the fact that she differs in numerous ways from the comics. Halle Berry's Catwoman, on the other hand, slipped so far from the character she became unrecognizable.
Generally speaking, the more accurate an adaptation can be, the better, as witnessed by the success of Netflix's The Sandman, among others. But that doesn't always have to be the case, especially when the changes are largely superficial. The recent announcement of a sequel in development for 2005's Constantine -- featuring a return of Keanu Reeves' unique take on the character -- is proof that canon isn't everything.
John Constantine began as a supporting character in Swamp Thing #37 by Alan Moore, Stephen R. Bissette, Rick Veitch and John Totleben and soon graduated to a line of his own. His Hellblazer comic was a staple of DC's Vertigo line for many years, and the character popped up in numerous other lines. However, when the time came for a movie adaptation, certain changes were necessary. It needed to convey Constantine to a wider audience, which meant things like narrowing its focus to Christian mythology and cutting Constantine's link to the larger DC Universe.
It also meant getting an A-list star to headline it. According to a contemporary report in Variety, Nicolas Cage was slated to play Constantine but dropped out only to be replaced by Reeves. Both actors represented a sharp visual departure from the comic book incarnation: a blonde cockney Englishman famously inspired by Sting. Cage and Reeves -- both dark-haired men -- rarely changed hair color to match a role. Furthermore, Reeves' ability with a British accent was suspect, having attempted one in Bram Stoker's Dracula with less than convincing results.
As a result, the character made his live-action debut as a dark-haired American with a radical change in background and motivation. In the comics, he gains magical powers from a combination of study and an ancestral bloodline and often gets haunted. Reeves' version is born with a second sight that allows him to see angels and demons. The torment of it induces a suicide attempt: giving him a glimpse of the hell awaiting him before being sent back. He battles demons to buy his way out of his fate, hoping to earn good graces with God by vanquishing the forces of Lucifer.
And yet, beneath the surface details, Reeves' Constantine is very much the same figure. He's cynical, caustic and manipulative and always looking for the angle in the supposedly pure motives of others. He's also well-versed in the supernatural -- to the point where it no longer holds any fears for him -- while demonstrating a skill for misdirection that often lets him outwit his opponents. And like his comic book counterpart, those close to Constantine have a way of ending up dead, something that doesn't help his eternally pessimistic outlook.
All of that can be seen clearly in Reeves' performance, despite the variation in appearance and background. It helped Constantine become a hit and sustain it as it grew into a cult classic. In the interim, Matt Ryan delivered a more comics-accurate version to much-deserved acclaim. Yet, even with that in hand, fans have welcomed news of a Reeves-centered sequel with open arms. Canon is important, but it doesn't define a project's quality.