New Old Flame

A gentle Retcon to allow a previously unmentioned love-of-their-life to pop up for a main character in an episode. Characteristically a Temporary Love Interest, this is a simple way to skip all the boring foreplay and jump right to the intensity.

Usually, it ends in death, Put on a Bus, death on a bus, or with some similar Reset Button.

Often, the character with the New Old Flame is already (re-)married, and it turns out it's not just the audience that's surprised.

Clumsily done, this can mess with the memory of a previous relationship carefully established over a Story Arc, and anger 'shippy fans.

The inverse situation, where the character does remember the love-of-their-life, but the reunion cures them of it, is Old Flame Fizzle.

Elegantly done, it can leave us with The Woobie.

Compare to Remember the New Guy?, Romantic False Lead.

Anime and Manga

 * Haruhi Suzumiya: Foreshadowed in the first novel, appears in the ninth.
 * Done in the Kannagi manga, triggering an absurd amount of Fan Dumb in Japan wherein people were burning their copies of the books simply because the character was no longer "innocent" despite the lack of anything sexual being mentioned in the story.
 * Done in Hayate the Combat Butler, concerning the past of and Hayate.
 * Except that, while Hayate still holds a flame for her, it's not clear if she has the same for him. And their former relationship was left at the point of her wanting to kill him.
 * This trope is the basis of Sekaiichi Hatsukoi where the main character works under his high school crush at his new job. Played with in that he does not even recognize that person.
 * In Soul Eater Marie's New Old Flame shows up. It appears like they both have leftover feelings for one another and are about to rekindle their relationship when said New Old Flame suffers from . It kind of serves to set of the Stein/Marie shippers, since Stein is the one who consoles her.

Comic Books

 * In the Daredevil comics, Elektra was introduced as Matt Murdock's previously unmentioned college girlfriend and love of his life. She died, but got better.
 * Lori Lemaris was this in the Silver Age Superman comics: Clark Kent's sweetheart from college (who turns out to be secretly an Atlantean mermaid).
 * Glittering Goldie is Scrooge McDuck's one true love. They break up due to Poor Communication Kills ... and some accident and bad choices and such. "The Prisoner of White Agony Creek", "Hearts of the Yukon" and "Last Sled to Dawson" show as much.
 * In the epilogue of Dark Reign, during the funeral of, Rogue reveals that they were in a relationship. Not only do her given reasons for the relationship boggle the mind, (there's a fair amount of people who can be in a physical relationship with Rogue and not get killed) but it's in incredibly bad taste since   was married. The whole thing feels like the writer is saying, "hey guys! This guy got to tap that ass! You should feel sad such a playa is gone!"
 * Billy Powers, an old high school boyfriend of Michael's, who turns up in the Ms. Tree story "Drop Dead Handsome". It doesn't feel especially forced as very little about Michael's high school days had been revealed. It ends about as well as any of Michael's relationships do.
 * A while back, we learned that Bruce Banner of all people had an incredibly hot girlfriend in college, but dumped her because he was a neurotic twit. She's now a Hot Scientist, and still bitter about the breakup.

Film

 * In Tomorrow Never Dies, the villain's wife, Paris Carver, is an old lover of James Bond. Given Bond's history, this probably happens a lot.
 * The titular Robin Hood and Maid Marian, who had been childhood friends and were in love before they were separated for some time and later reunited.

Literature

 * In the The Hollows
 * In L. Jagi Lamplighter's Prospero Lost, Ferdinand reappears. With even a reasonable explanition of why he didn't show up for their wedding. Then it turns out he's a fake, then it turns out -- let's just say this trope gets zigzagged in this work.
 * The Star Trek novel Shadows On A Sun brings back McCoy's ex-wife and has the start of a romance before
 * In Son of Summer Stars, eventually reconnects with  after  dies. It's all but outright stated to actually work out for them.

Live Action TV

 * Shau'nac/Teal'c in Stargate SG-1, "Crossroads".
 * Teal'c's wife, Drey'auc, is one of these in the first season.
 * Frasier's first wife in Cheers
 * And in Frasier, he seemed to have two different women who were his first wife. Both disappeared after the episode was over.
 * Sheridan's real first wife in the fifth season of Babylon 5.
 * Interestingly, in this case the "former wife" angle wasn't used for any of the normal reasons, but to explain why Sheridan knew he could trust.
 * This is brought up again in Crusade, just to tease Gideon about his hero.
 * MacGyver, at least twice, in "Flame's End" and "Jericho Games".
 * The same plot mechanism is put to different use (with shades of "Luke, I Am Your Father") in The Pretender episode "At the Hour of Our Deaths", which revolves around Miss Parker's adoptive sister -- never hinted at before, dead by the end of the episode, and never referred to again. The series also included several straight instances.
 * Lucille in the last two episodes of Chef served this purpose.
 * Reconstructed in River Song from Doctor Who. She is most likely a new old flame from the Doctor's personal future. When the Tenth Doctor meets her for the first time, she is extremely intimate with him right from the start, even knowing his true name and calling him sweetie and pretty boy. Then she  After he regenerates into the Eleventh Doctor, they spend several episodes flirting, during which Amy Pond decides she must be the Doctor's future wife. By the end of the fifth series, he may or may not have proposed to her. (He seems unsure himself whether he just did or not.)
 * And now, as of the end of the sixth series
 * Jack Harkness and John Hart on Torchwood, John is also Jack's Evil Counterpart.
 * Unsurprisingly, Jack has a few more of these. The radio plays gave us Stella Courtney (from 30 years ago) in The Dead Line, and the Duchess in Golden Age (very much a New Old Flame: he hasn't seen her since 1924, she hasn't aged a day.)
 * And again from the series itself, Estelle from the episode "Small Worlds". The twist in that case being that Jack is passing himself off as the son of her former lover (himself), apparently not wanting to explain his immortality to her. However, when she's  Jack is clearly heartbroken.
 * Plus, in Children of Earth, there's Jack's former lover and mother of his daughter. We never meet her as she has already died by this point, but she definitely counts.
 * Then there's Angelo in Torchwood: Miracle Day, who ends up the reason this whole mess started. Unfortunately, he comes back.
 * Ranger Ben served as one of these for C.J in The West Wing.
 * Happened in an episode of Angel when Doyle's ex-wife, Harry, popped in to get their divorce papers signed. Needless to say, Doyle's new love interest Cordelia was surprised by how much that bothered her.
 * Done heartbreakingly well in Due South with Victoria and Fraser at the end of the first season.
 * In season 2, Ray V's high school sweetheart, Irene Zuko, was introduced  in the episode "Juliet is Bleeding".
 * An episode of Mash had womanizing Hawkeye's "one true love" show up.
 * Used in the aptly-named Hogan's Heroes episode "Klink's Old Flame." It's played with, though: Klink hears that his old flame is coming to the stalag, but she is now married to an influential general. Knowing that if she rediscovers her old feelings for him, he could end up fired or shot, he takes drastic measures to make himself as unattractive to her as possible.
 * Lee Adama is angsty when he is reminded of his ex-girlfriend, whom he ran from after she told him she carries his child. Which is reasonable, just that he is the closest thing to a protagonist in this show, and the first time this is mentioned is the 14th episode of the second season.
 * In the minisodes we discover that Gaeta was involved with an Eight model Cylon on New Caprica. It doesn't end well. Although there's been no mention of this up till now, the webisode cleverly works in a previously unexplained Noodle Incident -- what Baltar whispered in Gaeta's ear before he found that The Pen Is Mightier.
 * Although not a lover, an episode of The A-Team does this strangely. One episode is based around the funeral of their old army buddy. There's a lot of tender reminiscing, and even a lingering close-up on a photo of the five of them standing together in uniform. This is made only slightly less poignant by the fact that we've never heard of this guy before, nor will we again.
 * A more traditional version of the trope is "The Only Church In Town", in which Face's first love Leslie Bektall turns up after a fifteen-year absence. (During which time she's become a nun. Ouch.)
 * The war buddy version is also seen in the Firefly episode "The Message" with Tracey.
 * Variant in Star Trek Deep Space Nine: Jadzia Dax and Lenara Kahn had technically never met before their one-episode romance, but the previous hosts of their symbionts were married.
 * Played straight in the DS9 episode "Profit and Loss", where Quark's old flame from the Bajorean Occupation, a Cardassian woman, returns to the station.
 * Dr. House and the now-married Stacy. More recently, it was revealed that Wilson has been dating his first ex-wife.
 * And as of season 7, Cuddy. However, the writers have returned everything to normal at the season's end.
 * Lise Hampton, Garibaldi's former significant other, shows up mid-fourth-season (after a brief mention in the first season) married to his new boss, William Edgars. To Garibaldi's credit, he kept things remarkably professional. In a strange twist (for this trope, not for the overall storyline, in which you could see it coming a mile off), Edgars dies (no, Garibaldi didn't do it) and the two get back together by the end of the season.
 * Not only that, but Garibaldi essentially inherits Edgars's financial empire, quitting as security chief and moving to Mars Dome.
 * Mad Men introduces an old flame of Roger Sterling's, whom he dated in Paris before the war.
 * Subverted in Earth: Final Conflict: William Boone's old flame appears after several years of absence and, in spite of Boone's wife recent death, he's unusually inflamed with passion, something extremely out of character for him. It's later revealed that the Boone's memories of their life together are false and were included in his cyberviral implant as a loyalty test by the Companions, and they had recruited an FBI agent to play the part of the former girlfriend.
 * It's also unclear if she really is working against the Taelons or was just saying that to test Boone.
 * An oft-ignored season one episode of Supernatural introduces us to Dean Winchester's ex-girlfriend Cassie. We get a glimpse of what Dean looks like in love, and it turns out he's kind of a sap. Sam has fun needling him about it until he realizes who dumped whom and why, and how badly Dean actually got hurt.
 * Another introduced Lisa, who now had a son with a suspicious resemblance to Dean, born about the right time after he knew her. . Lisa returns
 * In one episode of Castle, he and Beckett investigate a murder that took place during the wedding of one of Castle's exes.
 * Bobby for Hilda on Ugly Betty.
 * Casey has had two of these in Chuck.
 * Averted with Chuck's own ex, who was mentioned in the first 5 minutes of the pilot. Of course, he had no idea at that point that she was ; she also lied about sleeping with his best friend, who never bothered to deny it.
 * Charmed has a variant, where in the first season Prue's love interest is the same guy she dated in high school (which, since he's introduced that way right away, doesn't feel jarring). The "skipping foreplay" part is sort of deconstructed; they sleep together on their first "new" date, and while Prue is obviously embarrassed when she tells Piper about it, she argues when Piper says it's basically the same as sleeping with a guy on the very first date.
 * In Alias, Noah Hicks, Sydney's former partner, shows up for a few episodes at the end of Season One.
 * In Fringe season one, Olivia runs into a former flame, Lucas in "In Which We Meet Mr. Jones." Peter also has a run-in with a supposed past lover, Tess, in "The Dreamscape."
 * Amanda in Highlander the Series is introduced this way, early on. Duncan's current wife is not amused. (She later comes back after the wife dies, and they are a couple for much of the series.)
 * Det. Jo Rosati is Luke's ex-girlfriend in Rookie Blue. She joins 15th Division at the start of season 2 and forms a love triangle with Luke torn between her and his girlfriend Andy..
 * Tony's ex-fiancee Wendy showed up mid-season 8 of NCIS. Whether she will become the Romantic False Lead, or the actualy Love Interest, remains to be seen.
 * Malcolm in the Middle: Otto's conscience was finally starting to tormenting him for having tricked his rival out of the way so he could marry Gretchen. Otto then invited said rival over. However, when it turned out said rival was still in love with Gretchen all those years, Otto expelled him before Gretchen ever knew he came back.

Newspaper Comics

 * Many Modesty Blaise stories begin with the appearance of an ex-lover of either Modesty or Willie who needs help.

Video Games

 * In Trials and Tribulations, the third game of the Ace Attorney series, Phoenix and Mia each get one, Dahlia and respectively.

Webcomics

 * In The Inexplicable Adventures of Bob, Jean's ex-boyfriend Slick Simmons has recently appeared. He has some connection to the town's new lake monster.
 * Flipside: In Chapter 30, Bernadette encounters her former lover in Marvallo, revealing the reason for her neurotic insecurity about monogamous relationships.

Western Animation

 * Elita One from The Transformers, who showed up, helped Optimus Prime and the gang, and then was never seen again.
 * Although she sort of showed up in a later episode in the form of her younger self Ariel.
 * Zuko and Mai of Avatar: The Last Airbender (pun probably intended) -- textbook "skip all the boring foreplay and get right to the intensity." Contrast with the heroic Official Couple, who were in the foreplay stage for fifty episodes.
 * Subverted in that Zuko & Mai never so much as look at another romantic interest from the instant they're reunited, and are for all intents and purposes engaged to be married by the series finale.
 * And while they were probably joking, Word of God says that Suki once dated Foamy Mouth Guy. "She's not too proud of it..."
 * Désirée D'Allure, Monterey Jack's ex-fiancée from the Chip 'n Dale Rescue Rangers episode "Love Is a Many Splintered Thing". Complete with a Reset Button, yes.
 * Grandpa Lou in Rugrats had Morgana, who reappears several decades after leaving town believing he'd cheated on her. (The girl he was accused of cheating with later became his wife and is the deceased grandmother of the lead characters, but whether there was actual cheating or not is left entirely up in the air.) She only appeared in one episode, but was mentioned several times throughout the season before vanishing entirely.
 * From what I can remember, the girl who Grandpa Lou was "cheating on" had fainted (or maybe something of that sort) so he performed CPR. To Morgana it looked like he was making out with her.
 * Juandisimo was this to Wanda in Fairly Oddparents.
 * Lawrence and Linda in Phineas and Ferb are probably this. They appear to have been dating sometime in the early 90s, but they married to each other when they both had kids with other people