One of the most enduring series in American comics history is Preacher, the Vertigo series from the creative team Garth Ennis, Steve Dillon, Matt Hollingsworth and Clem Robins. It's the story of a young couple --- and their best friend, a chirpy vampire --- who go on a personal crusade against divinity, and the series takes on everything that comes at it: sex, violence, family, religion, war, hate, race. It’s powerfully made, a force of nature that rebels as hard as it can, creating a tale that's sensationally sordid and gleefully graphic.

And yet what’s most interesting about Preacher is that it takes a turn halfway through the run, almost abandoning the central conceit to give readers something unexpected. (Stop reading here if you don't want to be spoiled.)

Because it turns out that one of our heroes is actually the greatest villain in the book.

It can take a long time for the reader to realize, and even longer for the other characters to notice, but one member of our heroic trio isn’t a very nice person at all. In fact, he’s a scumbag, and his scummy qualities are exacerbated by the fact that he’s a coward about it, only partially admitting his failures as a way to allow himself to advance them.

I’m talking about Cassidy, of course; the quick-talking, hard-drinking vampire who is very easy to like when he first enters the story.

As the third lead alongside the star-crossed lovers Jesse Custer and Tulip, Cassidy takes the role of chaotic anarchistic who likes a bar fight and has a quick wit and an intense sense of loyalty. The characters are brought together immediately in the story, and established as three kindred spirits who will fight anyone who tries to cross them. Neither the readers nor the character realize at this early juncture that, just by having Cassidy in the team, the team is already betrayed.

Sure, Cassidy is a vampire, but he starts the series as a lovable Irish rogue, taking pot shots at the establishment in-between pints. Ennis slowly spins the character round to reveal something much more sinister; as we learn about Cassidy's history, his nature, and his horrible weaknesses, we learn that he's not the best pal who always has your back; he’s a self-serving misogynistic monster who can’t take no for an answer.

His initial interactions with Tulip are buddy-buddy and fun to read, but over time he starts to take more of a shine to her, and we see him try to charm her away from Jesse. She doesn’t take this very seriously, and neither do we, because all we see is the twinkly-eyed drunk who likes to have a laugh.

But once we realize that he’s serious, a veil slips from both the readers' eyes and from Tulip's. She tries to push him as far away from her life as possible, but he keeps forcing his way back in.

What’s most distressing about Cassidy is that his personality doesn’t drop once Tulip sees what’s going on. He’s still a rogue, only his lyricism now serves a sleazier purpose. The brilliance of the twist is that we get to see it happen early, just before Tulip does, and a long time before Jesse does. Preacher is often thought of as an all-in, full-blooded comic, but the real meat of the story is an incredibly slow burn. It’s about twenty-seven issues before Cassidy's slow exposure begins, and maybe another twenty before Jesse gets wise. Ennis plays the events out masterfully, stringing the readers along at the same time he cheats the characters.

We’ve all had friends who slipped away from us over time --- and we’ve all had that one friend who stays with you for years before you realize, hey, they’re not actually a very nice person. It’s horrible to realize you’ve spent your time passing off nasty aspects of a companion's personality as mere quirks, when in reality they’re evidence of a cruel, vicious, or self-serving nature.

That’s how Preacher manages to make Cassidy’s long-burn betrayal so effective: he charms the readers just as much as the character, so by the time he starts outright drugging Tulip and forcing himself on her, all we can think is, “Why didn’t we see this earlier?”

In his second issue, Steve Dillon depicts the full gory violence of Cassidy as he murders someone and drinks their blood --- and yet we're still not meant to see him as anything other than a fun character. His jokes are brazen, he seems an open book, and his vampirism makes him the perfect foil when fighting against Heaven itself.

But the Preacher team has a much different goal in mind for the series. Preacher isn't ultimately really about Jesse fighting God for control of everything.

The real battle for control that Ennis and Dillon are interested in here is between Jesse and Cassidy, and their weapons are their words. Jesse Custer may have had the word of God in him, but Cassidy had the gift of the gab, the very power of charm that he's used to conceal his cruel nature.

The most terrifying villains are the ones who don’t see themselves as villains --- it’s why the internet, with its anonymous hordes, is such a seductive place for our own worst instincts. It’s easy to be sucked into an identity and a sense of superiority… until one day you realize that your words have been causing real suffering and sadness for other people.

Not everybody eventually sees what they’re doing wrong, though, and Cassidy is basically a prototype for the MRA-types you see clogging up YouTube, acting like victims because they thin it's a way to power. Cassidy apologizes constantly for himself without an ounce of sincerity, his pleas for forgiveness allowing him to excuse his hunger. Once the reader turns on him, everything he does is magnified in obnoxiousness; what once made him so charismatic now makes him irreparably repulsive.

Preacher gets a lot of praise for the high-stakes take-em-all mentality that punctuates the series. But beyond that, it’s a startlingly subversive piece of work. The fact that Ennis and Dillon can make us root for the worst character in the book --- for thirty issues! --- is staggering, and it makes the knife in Jesse and Tulip’s back feel so much sharper. Cassidy is a cause you think you'd die for: it turns out he'll let you bleed out long before the fighting ends.