Promoted to Love Interest

So. You're adapting this great book for the screen. It's got action, comedy, drama, rom...what, it doesn't have romance? Well, that won't do; we can't break the formula. Looks like it's time for a previously platonic character to be Promoted to Love Interest.

This trope is a specific kind of Adaptation Decay. The idea is that in order to appeal to a broad audience, we need romantic subplots. An original and successful work (usually not film, because that's where executives have a field day) survived all on its own without a crappy romance subplot shoehorned in. However, Viewers are Morons when they watch something on the big screen, and obviously can't like a movie if the main character doesn't get to boink a chick by the end of it.

This sort of thing happens to everyone all the time in fanfiction, for some reason.

The trope in itself is not necessarily bad, but very hard to pull off effectively. When done poorly, this may become a Token Romance or even a Romantic Plot Tumor in the worst cases.

See also Hotter and Sexier. Compare Relationship Compression, where the romance is present in the original but significantly altered due to the different constraints of the new medium.

Anime and Manga

 * Oujirou in the Kidou Tenshi Angelic Layer anime. His girlfriend in the manga epilogue gets shoved off with Misaki's own love interest from the manga.
 * This happened somewhat to Yue Ayase in the Mahou Sensei Negima anime. While it was just barely alluded to in the Field Trip arc (which is where they likely drew it from), the love triangle plot come into play much later in the manga.
 * Valkyria Chronicles anime adaptation has promoted Faldio to love interest in order to introduce a Love Triangle. Not only totally unnecessary considering the existing romantic subplot, but it's become a rather large Romantic Plot Tumor. For instance, a rather epic battle in the game against an enormous overpowered tank was completely avoided in the anime to allow Alicia and Faldio time to flirt.
 * In the Tokko manga, Ranmaru and Sakura don't show any specific romantic interest in each other, but in the anime they develop feelings for each other and become love interests.
 * The closest thing to an original canon for Black Rock Shooter is a music video of the titular character fighting Dead Master. Once people started making actual stories, Dead Master ended up as the love interest in one manga, the "other self" of BRS's "other self"'s love interst in both anime, BRS's mother figure in the gag manga, and nonexistent in the game.

Comic Books

 * Liz Sherman from Hellboy. In the comicbooks, she's Hellboy's co-worker and friend, and something of a little sister. In the movies, she ends up boinking Hellboy. It did give her some character, since in the comics, she's mostly a Flat Character that the author has no idea to do with and only narrowly avoided killing off, and actually okayed the Retool of her character.
 * Interestingly, in the comics Liz actually has something of a romantic sub-plot with Abe Sapien, professional fish-person and Hellboy's best friend. Still, this sub-plot is extremely subdued, but it does get played up a bit in the animated adaptations.
 * In Ultimate Spider-Man, Kitty Pryde is one of Spidey's girlfriends briefly, giving him a relationship with someone he doesn't have to constantly worry about the safety of. They do break up eventually.

Film

 * Somewhat (and very surprisingly) averted in the movie adaptation to I Robot. Both the male lead and the female lead are very attractive, yet they never get romantically involved. Well, not explicitly, but there are hints at it, and Susan Calvin in the short stories was an elderly, celibate misanthrope after the first few Time Skips. She gets upgraded to a Hot Scientist, and at least a potential love interest, but thankfully they focused on the robots and the related ideals.
 * For the movie adaptation of Watchmen it was originally planned to give Rorschach a love interest since his actions drive the whole story. But the idea was dropped.
 * The 1960 film adaptation of H. G. Wells's The Time Machine is an Alternate Trope Namer. In the book, an Eloi woman named Weena shares a close relationship with the Time Traveler, but not a romance, at least not overtly. Largely because Weena, like all Eloi, was a child-sized androgynous-looking creature mentally on the level of an eight-year old. However, the film turns Weena into a love interest, looking human except still with the mentality of a child.
 * The 2002 film goes further: not only was Weena replaced with a love interest named Mara and the Eloi made even less childlike, but the Time Traveler was given an entire backstory of building the machine as a way to save his girlfriend from being killed by a mugger.
 * Isabella of France in Braveheart was in France and ten years old at the time of Wallace's rebellion. Particularly unfortunate as her romantic subplot is at cross-purposes with some of the most powerful moments in the film.
 * The 1966 film version of Ray Bradbury's Fahrenheit 451 not only had Clarisse, but also had her become a sort of love interest for Guy.
 * Not sure what Bradbury thought of the "love interest" part of it, but he considered rewriting the book to have her, and effectively did so with his theater adaptation.
 * Ellie Sattler is given a larger part and promoted to Alan Grant's love interest in the film version of Jurassic Park.
 * In a rare subversion, though, her role as a love interest is only subtly hinted at and the two don't end up together. By the third movie, Ellie Sattler is married (presumably happily) to a different man, and is raising a family.
 * In a move that savvy movie goers could have seen coming, the new Star Trek movie does this to Lt. Uhura. What they probably didn't see coming was that she's Spock's love interest, not Kirk's. Which is less surprising if you keep in mind a couple of early episodes of the original series in which she was blatantly flirting with him (and, more strangely given his later characterization, him with her!). Of course, given the time period of the original series, the only reason Uhura wasn't officially anyone's love interest was probably because of the interracial relationship thing. Word of God did once say he had dropped the idea of Spock/Uhura in the original series because he feared it would reduce Uhuru to being viewed as nothing more than "Spock's other half" instead of letting her being a character in her own right. Given how a lot of the fandom reacted to the romance in the film, his fears seem to have been justified...
 * Conversely, the movie didn't try to pair Spock up with Nurse Chapel, who had a crush on him in the series that was never developed due to the network objections (they didn't want the main male characters in any long-term relationships which ruled out both Spock/Uhura and Spock/Chapel, but which does explain why there were episodes that displayed Spock apparently flirting with both women (at different times) before it was knocked on the head).
 * The Film of the Book of The Chronicles of Narnia: Prince Caspian creates a romance between Susan and Caspian. Guess they didn't want to wait one more movie for Caspian's marriage to Ramandu's daughter. Fortunately, it's only a mild romance, limited to flirting and a goodbye kiss. It's so minor that it could conceivably have happened "between the lines" of the book, and it gave Susan something to do while she was onscreen.
 * Pretty much every movie version of The Last of the Mohicans de-ages Hawkeye and pairs him up with one of the female characters. Which is silly, because there's already a romance, two even, and he's not actually the main character anyway.
 * Maggie Barnes in the The Dark Is Rising movie.
 * Trillian in the film version of The Hitchhikers Guide to The Galaxy. In the original, Arthur met her at a party and tried to (clumsily) chat her up, only for Zaphod to sweep her off her feet and take her into space; when they meet up later on, their relationship is purely platonic. The movie changes this to Arthur missing his chance at True Love by being too wimpy, inspiring him to be more assertive when Trillian gets kidnapped (also helped by introducing a new love interest for Zaphod).
 * In the original radio series, Trillian was indeed meant as a love interest but things didn't progress the way Adams intended to. That's why their romantic involvement was played up in the movie.
 * Starship Troopers does this with "Dizzy" Flores who, in the book, is a guy in the same platoon as Rico, and is only mentioned in the first chapter, due to the fact that he dies during a drop, and is not romantic at all. (Per the other wiki and, you know, the book.) Of course, Dizzy gets an upgrade with boobs and boinked. It's good both ways.
 * In the movie of the children's book Tuck Everlasting, the main character, Winnie, is a teenager and thus old enough to have a romance with a Flying Dutchman who's been seventeen for ages. In the book, she was a preteen with perhaps a slight implied crush on him and nothing more.
 * Um, no. Unless we're talking about different people, Winnie is 12 in the books and Jesse is either 15 or 17. Of course, nothing physical happens but
 * The book was a bit ambiguous as to exactly how romantic things were on Jesse's end. Winnie definitely felt something for him, but it could very well have been a Precocious Crush. Let's just say that in the book, the two certainly didn't go running through a field and plan to climb the Eiffel Tower together.
 * Inverted Trope in Angels and Demons: is in bed with Langdon by the end of the book, but in the movie, romance is never hinted at.
 * The same was done in the film of The Da Vinci Code.
 * This is actually inverted in the movie adaptation of Psycho. In the original novel Lila and Sam become romantically involved Hitchcock made their relationship platonic in the film, because it would be gross otherwise.
 * In the 1982 sequel, though, Lila has married Sam and had a daughter with him, called Mary.
 * One of the changes made in the film version of Kick-Ass. In the film, he ends up boinking with the girl he's got a crush on.
 * Lord of the Rings. Okay, so Arwen was present in the books as a love interest but she wasn't present a whole lot. The movies upped that so she made an appearance (even if it was just in a dream/flashback/whatever) in every single movie.
 * The 1960 film version of Edgar Allan Poe's Fall of the House of Usher makes Madeline the fiancée of the narrator.
 * The film version of Queen of the Damned made the main subplot a romance between the two main characters who, in the book, do not speak.
 * One of the many things altered from the book is the identity of Jesse's maker. In the book, it's her "Aunt" Maharet (a distant ancestor-turned-vampire). In the movie, it's Lestat. This was obviously meant to reinforce the bond between the characters, which was never there in the book.
 * Harry Potter and The Deathly Hallows Part Two creates a new ship that wasn't in the original:  This may be J.K. Rowling throwing the fans a bone, since she originally said it wouldn't happen, but later on admitted that she could see where fans were coming from.
 * Averted in the film Shooter which is based on the Stephen Hunter novel Point of Impact. In the book Bob Lee Swagger becomes romantically involved with the widow of his old war buddy. In the movie the two become friends and allies, but they do not fall in love with each other.
 * The 2009 film of Land of the Lost has a truly bizarre version of this. Rick Marshall has a romantic relationship with Holly, who was his prepubescent daughter in the original TV show. The movie makes them unrelated and ages her up, obviously, but one wonders why they even bothered to call her "Holly" at that point.
 * In the 2009 film version of The Picture of Dorian Gray, Basil and Dorian finally get together. This is completely justified by all the deliberate Ho Yay in the original book, as at the time, Oscar Wilde could do no more than insert Homoerotic Subtext to let the reader know what was really going on.

Literature

 * As reported in Orson Scott Card's commentary on the Ender's Game audiobook, the main reason there's still no Ender's Game movie is because every producer wanted to age Ender to a teenager and/or give him a love interest, and the author rightfully refused to sign any contract that allowed anything of the sort.
 * Leaving aside the unfilmable indescribable nature of a lot of his stuff, this is probably the recurring problem with attempts at filming the works of H.P. Lovecraft, who was a very unromantic guy and didn't put any love subplots into his stories at all. Apparently, Guillermo del Toro's upcoming version of At the Mountains of Madness will avert this trope, which is why it took him so long to get the permission of producers.
 * Adaptations and pastiches featuring Sherlock Holmes always do this to Irene Adler, the one person to outsmart and upstage Holmes and to whom he refers to as 'the' woman. Although this is canonically along the lines of grudging admiration, when going off the source material and looking for someone to be Holmes' Love Interest it's either her or Watson... despite that in the one story Irene Adler is in, Holmes comes in laughing over Even if Holmes was into relationships, Irene seems pretty stoked with, but, of course, nobody cares what the woman wants. It seems that if they'd actually bothered to read the stories, someone like Violet Hunter would make more sense.
 * Well Watson shipped Violet Hunter, so it does make more sense, but I guess everyone loves someone who beats Sherlock Holmes.
 * Most adaptations of Dracula make Mina Murray Harker (or her equivalent, as sometimes her role and that of Lucy Westenra are flipped or combined) into the title character's love interest, a trend that's often attributed to Bram Stokers Dracula (the film), which made Mina the reincarnation of Vlad Tepes' bride Elisabeta. However, a similar incident occurred in the 1970 TV version, where Lucy looked like Dracula's lost love, and even the 1950s Hammer Horror version referred to Dracula in the posters as "the terrifying lover who died- yet lived!" In the book, there was indeed a vague indication that Dracula intended for her to become his queen, but Mina regarded this as A Fate Worse Than Death, complete with all the rape associations that went along with this.
 * Inverted in The League of Extraordinary Gentlemen, in which Mina isn't paired off with Dracula- but she still left her canonical Love Interest, Jonathan Harker, after he rejected her for being "ruined"... so that Alan Moore could then put her in a May-December Romance with Allan Quatermaine.
 * Which was doubly inverted in the movie, where Mina's husband is dead and she has no affair with Quatermaine. Sawyer flirts with her a bit and she did have an affair with Dorian Grey in the past, but it's implied that her years of living as a vampire have left her unable to really love anyone.
 * Flonne and Etna from Disgaea Hour of Darkness in the Disgaea novels. In the game the nature of their feelings for Laharl is very debatable, in the novels they both got a crystal clear crush on him.

Live Action TV

 * The TV version of Johnny and the Bomb adds a bit of a Toy Ship between Johnny and Kirsty.
 * Alice and the Hatter become a couple at the conclusion of Sy Fy's Alice.
 * Although it isn't the same Alice as from the books.
 * There have been several examples of a Saracen character appearing in Robin Hood stories: Nasir from Robin of Sherwood and Azeem from Robin Hood: Prince of Thieves, but in the BBC's Robin Hood the character is Gender Flipped into a Sweet Polly Oliver called Djaq. Sure enough, she ends up a Love Interest to at least two of the male outlaws.

Theater

 * The play The Solid Gold Cadillac had a relatively low-key romance between Mrs. Laura Partridge and Ed McKeever, even though the narration referred to the couple as "Cinderella" and "Prince Charming," who (of course) were married in the end. The movie version is much more of a romantic comedy, playing up the romance between McKeever and Mrs. Miss Partridge to an extent that the Tabloid Melodrama about the characters is fairly justified.
 * In the stage musical of Beauty and the Beast, Cogsworth and the wardrobe are portrayed as a couple, but are much more reserved about it than Lumiere and the duster.
 * In the musical of The Producers the previously minor part of Swedish secretary Ulla is not only expanded into leading lady but she becomes Bloom's love interest and briefly is the center of a one-sided Love Triangle between him and Max.
 * The musical adaptation of The Scarlet Pimpernel adds a romantic history for the villain Chauvelin and the heroine Marguerite, making the former something of The Vamp, since the latter used to be on his side. In the original novel, they were nothing more than acquaintances in the past and Chauvelin sees Marguerite as nothing but "a tool" now, his faith in her intellect to help him nab the Scarlet Pimpernel and his constant Terms of Endangerment aside.
 * In Seussical, Horton gets a lover interest in Gertrude McFuzz, a character from another of Seuss' books.
 * The Wicked Witch of the West and the Scarecrow are promoted to being love interests in the musical Wicked, based on a book of the same name. It seems really Squicky unless you've actually seen the musical . After that, it's all just an interesting Alternative Character Interpretation.

Video Games

 * Lumina and Rick from Harvest Moon. Lumina, the girl who appeared as a Lonely Rich Kid, who thought of you as her big brother and eventually fell in love with you, in "A Wonderful Life", was changed into a love interest for "Special Edition". She's changed from fourteen to sixteen(JP)/eighteen, and looks the same, though. Rick was just ran a tool shop in 64, but was changed to a love interest in Back to Nature For Girl.
 * When the Takarazuka stage adaptation Phoenix Wright was announced, fans who were familiar with the Takarazuka's penchant for adding in romantic subplots speculated wildly on who'd end up as Phoenix's love interest, with guesses ranging from the plausible (Mia, Maya) to the highly unlikely (Edgeworth). In the end, the one who got the promotion was, of all people, Lana Skye (well, they called her Leona, but if it walks like a Lana and quacks like a Lana...), a character who appears in only one case (albeit a fairly long one) and doesn't have any particular history or chemistry with Phoenix.
 * In the Mass Effect series, Garrus and Tali weren't originally intended as romance options. Fans liked them so much that they were added to the roster of possible love interests in the second game.

Western Animation

 * Bionicle usually follows the No Hugging, No Kissing rule to the extreme, but in the second and third movies, Matau noticeably flirts with Nokama quite a bit and there are some pretty noticeable hints that Nokama herself is into Vakama. The third movie also involves an Unholy Matrimony plot with the villains. (Other Bionicle media does include this stuff, but pretty much only to keep consistent with the movies. In the case of the Unholy Matrimony, Word of God writes off "marriage" as strictly political in this 'verse.)
 * Also in the first movie, there are some incredibly obvious hints that Hahli and Jaller like each other, though this was back before the hugging/kissing rule was really brought in.
 * And now that the story takes place in a world where there's no such thing as No Hugging, No Kissing, one of the female characters (well, the only one to ever get a spotlight, anyway) will show feelings toward the main hero, Mata Nui. Word of God says these feeling which could barely even be called love will only get referenced in one short scene in a novel, and their so-far friendly relationship won't go any deeper, since the storyline is still intended for a younger male audience (who, according to them, are still afraid of cooties), and since Mata Nui is an outcast from the no-romance world.
 * Happened to Spider-Woman in the Iron Man cartoon. Considering the Merchandise-Driven nature of the show, this was assuredly so that they could give Tony Stark a love interest who could get a toy. Especially awkward because in the comics Spider-Woman was a single mom.
 * Spider-Woman's daughter was in the cartoon as well. Her feelings about her mom's relationship with Stark were not shown (except in one episode where they have a fake wedding for some reason, and she's not happy).
 * Let's face it, the first season was just a mess. The second season makes the relationship much more realistic and has more characterization, though the second season is still not special compared to many 90's cartoon series.
 * The Spectacular Spider-Man averts this in the case of Mary Jane Watson. In the comics, she's one of several LoveInterests for Peter, albeit the one he finally married (until OMD, at least). In most adaptations, most notably the movies, she's given a greater role while the others are reduced, cut or combined with her. In Spectacular she goes with Peter to a dance in her first appearance, but is otherwise just a friend--the main love interests are Gwen Stacy and Liz Allan (plus some heavy-duty flirting from Black Cat when she appears).