It's easy to say Keanu Reeves is a product of his time. His chronically parodied mellow mien has vaunted works like Point Break and John Wick into the realm of classics, but have also led to deconstruction about the actor's persona and the attempts to break out of a preconceived mold. No actor embodies this give-and-take nature of celebrity better than Reeves.
With Reeves' career resurgence it's easy to forget the criticisms that were drawn from the few times he went into the opulent world of literature, and yet he did. Serious adaptations like Bram Stoker's Dracula and Shakespeare's Much Ado About Nothing tested the actor's mettle, and even works like the Devil's Advocate, a modernized take on Paradise Lost, have shown Reeves' acting range regardless of how out of place he appears to be.
His turns in outright literary adaptations leave him as the ultimate stranger in a strange land. Francis Ford Coppola's 1992 adaptation of Bram Stoker's vampire novel, Dracula, is best known for its rich set and costume design, coupled with its all-star cast. Though Reeves' English accent is wonky, a critical note that followed him as he took on the world of Shakespeare, it works with this source material.
In Stoker's novel, Jonathan Harker is a civilized man trapped in the macabre world of Count Dracula (played in the film by Gary Oldman). Harker is meant to represent all that is good and pure about being a white male from England. (Stoker's work is heavily dated against anyone who isn't a white male) As Harker, Reeves is left to mainly look scared and be terrorized by the Count and his brides. He is the babe in the woods waiting to be defiled and tormented ⏤ his soul always in chronic peril. Though Reeves had done a few indie dramas up to this point, most prominently in Gus Van Sant's My Own Private Idaho, he was perceived as dumb and naive. As Harker, this was perfect since the character starts out as a young lawyer who scoffs at superstition and the concept of vampires. For audiences watching, you bought into the movie's premise because Reeves was without guile. If he couldn't sell you on the character through his innocence, then the movie would fail completely.
This might explain why, his villainous turn as Don John, in Shakespeare's Much Ado About Nothing doesn't work. The Bard's comedy of manners sees Reeves play the bastard brother of Denzel Washington's Don Pedro. Almost immediately the polished yet naive look of Jonathan Harker is replaced by a cold, cool, sharpness as Don John. There's almost an operatic personality to Reeves' look which is mimicked in his performance. To his credit, Reeves did try to get the cadence of Shakespeare's dialogue, and as he articulates his plans throughout the movie he says the dialogue with the required grit and aggression the film desires.
But where Harker was a conduit towards emphasizing how terrible and frightening Dracula is, Don John himself is meant to be the frightening one and fails. Reeves comes off as far too modern and, at times, buffoonish. In one often maligned sequence, Don John describes how devilish he is while getting a massage. The scene is odd as it ends up emphasizing Reeves' body and attractiveness. A move to entice young girls who were in the theater, perhaps? But it ends up stripping the character of any menace he would ordinarily have. He's too pretty, and he's too modern for the audience to conceivably buy within the confines of Shakespeare.
If you're asking how he's too modern for Shakespeare and acceptable for Stoker, it boils down to the language. Coppola's Stoker film certainly has formal dialogue, but the phraseology isn't as ingrained in our public consciousness like Shakespeare. When watching an adaptation of one of Shakespeare's features we're aware of the dialogue, even if the film is modernized. For audiences of 1993, Reeves had been sold as a hyper-idealized representative of modern American youth in the likes of Bill and Ted's Excellent Adventure and Point Break. For better or worse, audiences could only divorce themselves from Reeves' "whoa!" persona so much. It was enough to give him an accent while still having him speak modern English; it's another can of worms to make him dance around Shakespearean dialect.
This isn't a criticism of Reeves himself, though he does seem a tad uncomfortable in Much Ado. It's a criticism to audiences who, no matter what they may think, do buy into and create Hollywood personas for their favorite actors. No matter how a film fan may believe they don't buy into Hollywood hype, an actor like Reeves ⏤ who clearly can or can't be bought into a particular film role ⏤ is indicative of that.
Which leads us to the perfect unity of literary conceit and persona, 1997's The Devil's Advocate. A popcorn movie with a literary background, Taylor Hackford's feature sees a hotshot lawyer (Reeves) deal with moving to the big city to pursue a job opportunity. As things develop, Reeves' Kevin believes his boss (Al Pacino) might be the Devil himself. The film is a loose adaptation of the epic poem Paradise Lost and unlike Dracula or Much Ado the lack of awareness on the source material is a benefit. (As someone who loves Paradise Lost, it pains me to admit not many people have actually read it.) However it fits in with Reeves' persona. His slick coolness that doesn't come across in Much Ado feels fitted to the role here, possibly because the character isn't actually based on anyone from Milton's original poem.
Reeves could have let how an audience perceives him color the choices he's made. Yet his attempts to engage with classic literature have challenged both his work as an actor and how far audiences will (or won't) go in the suspension of disbelief. Regardless, all three of these films are fun and memorable, if for Keanu than anything else.