Chemistry is indefinable, but you know it when you see it. It doesn’t have to be romantic; you can even feel it with someone you don’t particularly like. And it’s not necessarily about appearances, because chemistry can exist between two people who are wildly dissimilar in beauty. Woody Allen (not exactly a heartthrob) has it with Diane Keaton. Adam Sandler (considered totally undateable by plenty of women) has it with Drew Barrymore. Often chemistry occurs in the moments between when things are said. It lies dormant in what is unspoken, in looks exchanged between two people. That’s what makes it so difficult to describe.
The film adaptation of beloved BDSM best-seller “Fifty Shades of Grey” opens this Valentine’s Day weekend, amidst accusations that the film’s leads, Dakota Johnson and Jaime Dornan, don’t have any sparks. When interviewed or pictured together, there has been a notable lack of jesting. They both seem pretty serious and buttoned up (ironic, considering the film’s subject matter). Of course, even animosity can result in lively chemistry on screen: Rachel McAdams and Ryan Gosling claim they hated each other when they were making “The Notebook.” Reviews of “Fifty Shades” report the magnetism between Johnson and Dakota isn’t bad, but the story is too dull for it to be entirely convincing.
In honor of this holy day of love, we’ve compiled a list of the best and worst examples of chemistry at the movies.

Kate Winslet and Leonardo DiCaprio in “Titanic” (1997)
Like it or not, the zenith of modern movie chemistry is probably Kate Winslet and Leonardo DiCaprio in “Titanic.” DiCaprio has often demonstrated impressively terrible chemistry with famously beautiful women (Carey Mulligan, Cameron Diaz, Marion Cotillard, Claire Danes). Yet something about his combination with Winslet resulted in one of the most scalding hot love affairs in silver screen history. I’m still not convinced the two of them aren’t in love. Their energy when opposite one another is electric; they rise above James Cameron’s cheesy multi-colored sunsets and make the film a masterpiece in its own right. Not only do their sexy scenes resonate, but also the clumsy desperation with which they attempt to stay together when the ship is sinking (a.k.a. the best part of the movie). They are endlessly running, panting, grasping at each other’s bodies, trying to stay side by side. Neither particularly cares whether they live or die, as long as they do it together. Jack (DiCaprio) shows Rose (Winslet) a crooked pathway leading away from her privileged upbringing. He shows her how to have fun; and she, in turn, introduces him to headier, sensual pleasures. In Rose, Jack recognizes a kindred adventurer, a pioneer, a mighty force. Even better—he forces her to see that in herself. Winslet and DiCaprio became great friends in real life, accounting for their magic on screen when they reprised the role of lovers in “Revolutionary Road.” Sadly, Winslet seems to prefer older men off camera and DiCaprio chases younger model types. Maybe they could only ever make it work in fiction. But when Winslet won her Golden Globe for “Revolutionary Road,” a film where their chemistry sizzled like in “Titanic” but in an even sadder way, she arguably thanked Leo more profusely than she did her husband Sam Mendes (who directed the film) in the acceptance speech.

Jake Gyllenhaal and Heath Ledger in “Brokeback Mountain” (2005)
Ang Lee’s sensitive direction of this slight, delicate love story certainly had something to do with making “Brokeback Mountain” a hit—but it’s the chemistry between Jake Gyllenhaal and Heath Ledger, two straight men who had never before played gay or bisexual characters, that really rendered the film an instant sensation. In a time when it wasn’t yet “cool” to play a gay character (only ten years ago, if you can believe it), neither actor balked at the challenge or held anything back. Ennis Delmar (Ledger) is a gruff, silent cowboy who can barely spit out his feelings no matter how important they are. He’s afraid of nearly everything he’s ever felt, and that fear propels him to cave in on himself. When he meets Jack Twist (Gyllenhaal), he doesn’t want to be drawn out of his shell; but Jack is insisting, sweet, and guileless—and soon, the two of them are in love. “Brokeback Mountain” is powerful in part because of the love story’s suppression; Jack and Ennis never outright admit they are in love. They have to hide it. When they kiss, they mash their faces against each other with a mad sort of urgency. They know how difficult, even impossible, it is for them to be together, and so they steal moments in time, squirreled away in the mountains with no one but the trees as witness to their lovemaking. These are two incredible actors, flexing their muscles on screen in two of the best roles they’ve ever had. Gyllenhaal has since moved on to push himself to extremes with projects like “Nightcrawler.” Ledger, after dazzling everyone as the Joker in “The Dark Knight,” passed away. He probably had many more such performances left in him, but we’ll never get to see them. Like Jack and Ennis, whose love also never made it to fruition, all we’ve got now is “Brokeback Mountain.”

Ethan Hawke and Julie Delpy in “Before Sunrise/Sunset/Midnight” (1995-2013)

Werner Herzog and Klaus Kinski in “My Best Fiend” (1999)

Ryan Gosling and Shareeka Epps in “Half Nelson” (2006)
Not all chemistry is strictly sexual. “Half Nelson,” a terribly underrated little powerhouse of a film directed by Ryan Fleck, features one of Ryan Gosling’s most interesting performances and connections with another actor to date. Dan Dunne (Gosling) is an impassioned inner city school teacher and functioning drug addict. His student, Drey (Shareeka Epps), is perhaps his only friend—though this is a line he is weary of crossing, because he’s her superior. This isn’t one of those inspirational teacher/student stories where everyone triumphs over adversity. Dan intermittently encourages and deeply disappoints Drey, who is tough and guarded. They ‘get’ each other and they can get through to one another. Dan is even more messed up than the kids he’s teaching, but he’s honest with them, Drey especially. He isn’t ready to be a father figure, though he can be a friend. Watching Dan struggle with his addiction and subsequently lonely life, Drey seems to shy away from following in her own family’s footsteps. She doesn’t want to end up like her brother (who is in prison). The film is right not to let anything titillating or boundary-crossing happen between the characters. Sure, if Drey was older, she and Dan would be great together. Yet this is a deeper kind of allegiance. When they’re together, neither character says much—but somehow we know exactly what they mean.

READ MORE: The 11 Best British Romantic Comedies
Go to page 2 for WORST chemistry…
Worst Chemistry:

Ben Stiller and Greta Gerwig in “Greenberg” (2010)

Ryan Gosling and Michelle Williams in “Blue Valentine” (2010)
A lot of people seem to think Derek Cianfrance’s “Blue Valentine” is a beautiful romantic tragedy, but the relationship between Dean (Ryan Gosling) and Cindy (Michelle Williams) is actually incredibly depressing. The script could certainly be part of the problem, but much of the dialogue was improvised by Gosling and Williams. Specifically, the trouble is that we can’t mourn the loss of a couple’s happiness if we never see them being happy in the first place. These two are glum and sluggish almost all the way through the film, most notably Cindy; she doesn’t even seem to like Dean that much. And Dean is so dissatisfied with himself, there’s no way he could properly love anyone else. Their lives are sad and empty and so are they. Williams’ Cindy doesn’t even feel like a real person. The actors seem to be playing characters much less intelligent than their real selves, and that’s a tough thing to do, without losing depth and dimension. They don’t pull it off.

Julia Roberts, Clive Owen, Natalie Portman, and Jude Law in “Closer” (2004)

Joseph Gordon-Levitt and Zooey Deschanel in “(500) Days of Summer” (2009)
Seth Rogen and Katherine Heigl in “Knocked Up” (2007)
It’s hard to believe Seth Rogen and Katherine Heigl as a couple in Judd Apatow’s comedy “Knocked Up.” Ben (Rogen) and Alison (Heigl) have a drunken one-night stand resulting in an accidental pregnancy, and they decide to have the child together. Presumably, the film’s rom-com premise rests on them falling for each other against all odds, but sadly they seem to stay together mostly because they are both too lazy to do better. Alison has no discernible sense of humor; she’s self-righteous and dull. Ben is immature and lazy, but at least he’s a nice guy. There’s no reason he would stay with a woman who treats him this badly, other than she’s a lot hotter than he is. Heigl can’t summon even a smidgen of convincing interest in Rogen; it’s hard to tell whether it’s the character who feels nothing but disdain for him, or Heigl herself. Rogen’s Ben strains to get her to like him, but you get the sense he’s only doing it to avoid further drama. Ironically, Rogen has great chemistry with Paul Rudd, who plays Pete, Alison’s brother-in-law. “Knocked Up” features two women (Leslie Mann as Debbie, Alison’s sister) who seem to inexplicably hate men. At the very least, they hate both their own partners, and each other’s. The relationships are co-dependent, but noticeably unpleasant. Both female protagonists are decidedly uncool, bitterly lashing out when they can’t understand Ben and Pete’s DeLorean time machine references. Come on—girls like “Back to the Future,” too.

Everyone in “Troll 2” (1990)
“Troll 2” is a low budget cult classic, infamously dubbed “the worst movie of all time.” And it really is. But it’s also the best. Directed by Claudio Fragrasso, the story follows a family vacationing in a small town called “Nilbog” (yes, that is goblin spelled backwards). The town’s inhabitants are goblins in clever disguise, and they plan to eat the unsuspecting visitors—but first, they feed the family tainted green food and drink, which turns them into plants, because these are vegetarian goblins (note: despite the title, there are no trolls in the film at all). The rest of the plot defies logic or explanation. The actors seem to be embroiled in an unspoken competition with each other over who can be the worst actor. They say their campy lines robotically, and none of them bear any passing resemblance to actual human beings interacting normally with each other. Fragrasso and his Italian crew spoke very little English, so the American cast had no idea what was happening on set; additionally, the actors were non-professionals, seemingly selected randomly (one man made an appearance in the film just days after being released from a mental hospital). “Troll 2” is absurd, but fascinating. And it’s memorable—in an age where we’re inundated with movies and TV, much of it forgettable, it’s refreshing to find something silly that will forever stick in your brain.
READ MORE: 11 of the Most Unconventional and Innovative Romantic Comedies
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