The Dating Do Si Do is the tendency for a long running piece of fiction to recycle characters. In shows dealing with relationships especially, the tendency is that the longer the story goes on, the greater the likelihood that everyone will at some point have been in a relationship with (or at least slept with) everyone else. Well, usually not quite everyone, but still, the number of people having been in a relationship with other people is probably greater than could be expected under normal circumstances.
Usually it seems to be done to avoid introducing new characters. Unlike a Love Dodecahedron, a series that enjoys this dance does not necessarily have any of the couples being in competition with each other.
As can be noted, this is especially common in long-running series that still keeps a fairly regular cast.
Named after the Do-si-do, a figure in several dances that involve the dancers switching partners.
- Lots of comics have this to some degree, but the best example would have to be Spider-Man. All of Peter Parker's girlfriends (except Deb Whitman) have dated other members of his supporting cast at various points. Sometimes multiple members of said supporting cast. Spider-Man: The Animated Series rectified this oversight by adding some Will They or Won't They? between Deb and Flash Thompson.
- In the reimagined Battlestar Galactica, most of the main characters go through a series of relationships with everyone else, sometimes at the same time. Lee and Kara stand out as particular offenders of the trope.
- Played with in Friends. Almost all of the straight, non-incest pairings had a Ship Tease, though most were Played for Laughs, and almost all the characters have kissed each other. But only three pairs (Ross/Rachel, Monica/Chandler and Joey/Rachel) were treated seriously and actually happened. Given the show ran for ten years, the writers did pretty well at not having the characters constantly date each other.
- In Coupling, Susan dated Jeff (once), Patrick, and Steve; Steve dated Jane and Susan; and Patrick has been involved with Susan, Jane, AND Sally.
- Buffy the Vampire Slayer. Name any two characters (including characters of the same sex), and they'll either have been canon at some point or have a (sometimes very small, but still there) fanfic following.
- Lampshaded in the final season: "Is there anyone here that hasn't slept together?" note And Xander and Spike (who shared a one-room basement apartment for several months) just stare at each other...
- Gossip Girl, complete with an actual chart on the Gossip Girl blog. Lampshaded whenever they have to explain it to someone new.
- This is mostly averted in the Noah's Arc series, but played very straight in the movie with lot of sexual crossovers between Noah, Wade, Baby Gat, Chance, Ricky, Brandon, and Eddie (basically all the main characters except Alex).
- On Sabrina the Teenage Witch Mr. Kraft dated both Hilda and Zelda at different times. Sure it's dramatic, but we'd hate to be in Sabrina's position on that one.
- Popular, though it was a high school show and perhaps a Justified Trope. That said, boy, Josh did sure get to make out with/boink what, all the female cast short of April Tuna?
- Degrassi the Next Generation. See the picture above. Note that the prominent use of gay and bisexual characters, along with several cast herds is almost enough to make the entire thing circle in on itself. We pray they never involve Time Travel. Was originally the Trope Namer.
- The L Word fits this one quite nicely, especially "The Chart", which basically kept track of all their partner switch-ups.
- That '70s Show had a pretty tame version of this, mostly centering on how by the end of the show's run, Jackie dated three of the four young male regulars. More notable was the lampshading — see the page quote. The What If? episode makes it a little more complicated, revealing that Hyde would have started dating Donna if Eric hadn't kissed her at the end of the first episode.
- Two Guys and a Girl (not to be confused with the trope with the same name) had this to the extreme in the final few seasons. Pete had gone through 3 girlfriends, fell in love with the eponymous "girl" Sharon, and had sex with Berg's mom and ex-girlfriend. To say nothing of the cavalcade of women Berg went through.
- Glee: Let's see... the show explored Finn/Quinn, Finn/Rachel, Rachel/Will, Puck/Rachel, Puck/Quinn, Puck/Mercedes, Rachel/Jesse, Puck/Santana, Brittany/Santana, Finn/Santana, Kurt/Brittany, Terri/Will, Emma/Will, Emma/Ken, Will/Shelby, Quinn/Sam, Artie/Tina, Mike/Tina, Sam/Quinn, Artie/Brittany, Emma/Carl, Will/Holly, Rachel/Blaine, Sam/Santana Kurt/Blaine, Santana/Karofsky, Sam/Mercedes. All in the first two seasons. Lampshaded more than once by Emma.
[Kurt and Rachel come to Emma holding hands. (Kurt is well known to be very gay.) ]
Emma: I thought this day would come. This is the only dating combination the glee club hasn't tried!
- Angel, like Buffy, is full of this. Cordelia was in love with Angel, slept with his son, and had some UST with Wesley back in their Buffy days. Fred had a crush on Angel, and dated Gunn and then Wesley (who had been sleeping with Lilah). Darla was Angel's sire and his lover for 200 years; Lindsey was briefly infatuated with Darla (possibly as a transference of his obsession with Angel), and was later a couple with Eve, who slept with Angel. Angel and Spike were both in love with Buffy, and both had been involved with Drusilla, and then there was that one time...
- When a new person asks if they have a chart, Gunn responds "In the files. I'll get it for you later."
- Israeli suspence-action-drama series HaShminiya (The Octette in English) has this. At one point, one of the character's older sister comments, "Is there any combination in the Octette you havent tried yet?"
- Bones: Angela and Hodgins dated, then Angela dated Wendell then she dated Hodgins again. Cam dated Booth (twice), who then eventually dated Bones. Cam eventually went on to date Arastoo. Off in their own little corner is Daisy and Sweets who dated for quite a long time on and off. Sweets dated Jessica Warrwn for a bit, then reunited with Daisy before his season 9 death. Jessica later dated Aubrey.
- Something of a subversion in The Big Bang Theory. Considering Penny was the only female of the cast for some time, shipping her with the rest of the male cast would have troublesome implications (and she already fights a losing battle that she Really Gets Around). She was hit on, at one point or another, by every guy except Sheldon, but it always ended with pairing getting shut down quickly, except with Leonard. Later in the show's run they added Bernadette and Amy to the cast as love interests for Howard and Sheldon. They have similarly addressed possible alternate pairings (most notably Raj and Bernadette) but with nothing actually happening.
- Addressed in Last Man Standing. Kristin and Kyle dated during the first season, breaking up amicably at the end. After some progressive Ship Tease, Kristin's sister Mandy started dating Kyle. Unusual for the trope, Mandy has to admit to herself that she likes Kyle and, from there, goes to Kristin for permission to pursue him. Kristin is more worried about Kyle than Mandy, as he is a Nice Guy and she is know to be a big flirt. While by and large it all works out, tension still flares up from time to time because of that history.
- On Petticoat Junction Steve dated the eldest Bradley sister, Billie Jo, for a while, but later as they drifted apart, he fell in love with her baby sister Betty Jo. Naturally their mother was a little upset about this development. To his credit he eventually married her.
- Throughout its eight-year run,The Vampire Diaries was the absolute master of this trope, despite starting off with one solid Official Couple, Stefan/Elena. You can pick any two characters of the opposite sex from the main and recurring cast, and there's a pretty good chance they've been romantically linked at some point. It gets especially bad in later seasons, where the show seems to pair up any two people who are both single at the same time, regardless of whether or not they've ever shown interest in each other before that season. The most egregious examples of romantic musical chairs among the main cast on this show include:
- Elena dated Matt, then Stefan, then Damon, in that order. Matt dated Caroline, who then dated Tyler, then slept with Klaus, then dated Stefan, then got engaged to Alaric, then dated (and married) Stefan again.
- Stefan himself went through Katherine, Rebekah, Elena, then Caroline.
- Tyler dated Vicki, Caroline, and Liv.
- Jeremy was in love with Vicki, who was dating Tyler at the time, then Anna, and finally Bonnie, his sister's best friend.
- Alaric was married to Isobel, Elena's biological mother, then dated Jenna, Elena's aunt, was romantically linked to Meredith for some time, almost married Jo, then got engaged to Caroline, his former student.
- In The Magicians (2016), just in the first season we get Quentin and Alice in a relationship as well as Penny and Kady, plus Quentin has a three-way with Margo and Eliot and as revenge, Alice sleeps with Penny. Later seasons give us Alternate Timeline Penny and Julia, Margo and Josh, and Quentin and Eliot have feelings but Eliot rejects him before Quentin's death.
- This is the entire raison d'être of Diesel Sweeties. Even Metal Steve, the cast virgin, got in on the action until his surprise marriage to Allie V.
- In Batman Beyond, Dana is the only recurring character with only one love interest. Even her steady boyfriend wanders from time to time. Alpha Bitches Chelsea and Blade seem to have a new boyfriend every episode, frequently each other's previous flames. Nelson Nash also bounces between girlfriends more than once.
- Total Drama World Tour: mostly consisting of Gwen, Duncan, Courtney, Alejandro, Heather, and possibly Tyler, Cody, and Sierra.
- But considering the fact that the writer for Total Drama was the original writer for Degrassi: The Next Generation, this shouldn't come as a surprise.
- Archer: There are, mathematically, twenty-one ways the seven main characters (Sterling, Lana, Malory, Cyril, Cheryl/Carol, Pam, and Krieger) could pair off; of these, a third have actually happened. Lana, Cyril, Pam and Carol/Cheryl have each had half of the other six.
- Pam takes a while to get into the game though, during the first season or so her bemoaning the fact that nobody would sleep with her despite this trope was something of a Running Gag.
- The Spectacular Spider Man - basically all teens dated more than one person with the sole exception of Randy and Sally and Hobie Brown, who remained single.
- The Legend of Korra has a mild example: Bolin tries to date Korra, but she rejects him because she's interested in Mako. Mako and Asami date, but break up in time for the Book One finale, establishing initial Official Couple Mako and Korra. Only for them to break up in the next book; afterwards, Mako and Asami have a brief fling that is quickly ruined when a semi-amnesiac Korra returns and kisses Mako, believing them to still be together. Mako doesn't mention that they broke up, destroying his chances with Asami, and to top it off, in the finale he and Korra break up for good. The entire mess serves as a great way for Korra and Asami to bond during Book Three, and the Grand Finale of Book Four has them get together instead.
- At some colleges (even stereotypically unsocial and nerdy ones) this can hold disturbingly true. Even if there are no social cliques, there will be sexual cliques. If you make this graph with math majors, they'll call them clusters.