Birds of a Feather

""Birds of a feather flock together.""

- Folk saying

"Grace: My mum always said opposites attract.

Rich: That's magnets. We're people."

- Rich and Grace of Skins comparing this trope and Opposites Attract

Relationships, particularly romantic ones, tend to thrive when the people involved are similar. People are simply more likely to get along if they share common interests, values, beliefs, and goals. Thus people with similar personalities will often flow together easily.

The dynamic of this pair differs widely from Opposites Attract pair. Their personalities can often be interchangeable and both of them can have a same role if they are a part of a group. However, their common obstacle is having a harder time to compensate for each other's weaknesses.

Be warned, writers: while often Truth in Television, this trope can sometimes be seen to create a poorly written Love Interest who just happens to be a Gender Flip of the main character.

Not to be confused with the Sitcom of that name.

Popular Birds Of A Feather dynamic tropes:
 * Twice Shy
 * Certain types of Belligerent Sexual Tension
 * Pair the Smart Ones
 * Just Friends
 * Lookalike Lovers

Anime and Manga

 * Kou and Aoba from Cross Game they have the same hobbies, similar personalities, constantly snark at each other, and have a tendency to independently come up with the same solutions. And just about everyone points out how similar they are.
 * Lenalee and Allen from D.Gray-man are pretty similar in personality (especially in the manga). They're both pretty serious (although Lenalee is a bit more so), both have moments of Get a Hold of Yourself, Man! (with one slapping some sense into the other, and the other apologizing and thanking them), and they both have very similar goals and views. Also, love relationship-wise, they're both very not aggressive, and tend to be extremely shy. If they were to get together, it would be pretty hard to say who would wear the pants in the relationship, honestly.
 * Train and Saya from Black Cat became very similar. Initially, Train, although having a nice nature at heart, repressed much of his feelings and wasn't very expressive other than being angry. However, after spending some time with Saya, he quickly became Genki like her, even choosing to go after the same job as her and apply the same principles and morals she had. Near the end, Train becomes so much like Saya to the point where Creed actually sees a ghostly image of Saya juxtaposed on top of Train. Although their relationship might have possibly evolved into a romantic one, it... didn't.
 * Tsuna and Kyoko from Katekyo Hitman Reborn aren't really very different in personality. They're both determined, both naive and good natured, and both very oblivious to other character's feelings for them (In Kyoko's case, Tsuna's feelings for her; In Tsuna's case, Haru and Gokudera's feelings for him). But due to how similar and flat their relationship is, many fangirls took the liberty of pairing Tsuna with pretty much any or all of the other male characters in the series.
 * It doesn't help that due to Art Evolution, Tsuna and Kyoko are now practically twins.
 * Other than the height difference, Risa Koizumi and Atsushi Otani from Lovely Complex are shown to be extremely similar in personality.
 * In Code Geass, Lelouch and C.C. resemble each other in many ways. They both have Geass powers, they are both angsty, both have problems with their admirers / love interests (Mao and Shirley, respectively, and later Rolo), and both tend to have rather calm demeanors. One of the traits that is the most similar between them is that they are both very lonely individuals. Lelouch even comes out and says to her, "You're not alone. We are accomplices. If you are a witch, then I am a warlock!"
 * Suzaku and Euphie. Their goals are the same, they have a very similar sense of humor, and they get serious about the same things. Not to mention a moment in the anime, where they're shown to say the same thing at the same time, only to both burst out chuckling.
 * Sensui and Itsuki of Yu Yu Hakusho. Two psycho Manipulative Bastards who don't really fit in anywhere else...
 * In the Manhwa Threads of Time, Atan Hadas falls in love with protagonist Moon-Bin because (due to being from the future) he is open-minded about women's rights, kind hearted, and dislikes unnecessary violence. Because she is an outgoing Tsundere who wishes people would see women as equals, she finds him refreshing and wonderful, calling him her "precious confidant," and loves talking with him because they have similar views. To further this trope, she hates Sali Taiyi because of his chauvinistic views and horribly violent ways.
 * Momoka and Tamama are described as being this in Keroro Gunsou. Both of them seek love from someone else but fail, and both have split personalities.
 * Does it still count if they're not in love with each other?
 * In Fruits Basket, Mitchan and Ritsu are both hyperactive, hypersensitive, and wallowing in Heroic Self-Deprecation. Naturally, it's Love At First Sight, just about.
 * In Full Metal Panic, this is one of the reasons Gauron implies to be why he's Sousuke's Stalker with a Crush. In many ways, they are very similar. They're both war veterans that went through very violent, bloody battles and killed many people. They're both experts at piloting AS. They're later shown to both be working for organizations that hire mercenaries (though their organizations are always opposite and always clash with each other, making them destined enemies). Of course, the main difference is that Gauron is Ax Crazy and Sousuke doesn't care for murdering people.
 * One of the more recent arcs of Naruto has the title character develop a Intergenerational Friendship with Killer Bee who, with all intents and purposes, is an adult version of Naruto.
 * This appears to be the main appeal of the Greece/Japan pairing in the Axis Powers Hetalia fandom (well, aside from the "private lesson"). They both have quiet, subdued personalities and share a love of cats, and they're about the only teased-at couple that doesn't have a Tsundere or clear-cut Opposites Attract dynamic.
 * What makes this interesting is that the two are actually opposites in many ways (they do come from separate continents and cultures, after all) but are still similar enough at their core (it's amazing how well a lazy, spacey Greek who Really Gets Around and a hardworking, focused Asian who Hates Being Touched will get along when said Greek is a Nice Guy and said Asian a Yamato Nadeshiko deep down) that they don't butt heads over their differences like most other couples/pairings from the series do, but instead accept or even appreciate them.
 * Non-romantic example from Fullmetal Alchemist- Sig Curtis and Major Armstrong hit it off immediately, both being Gentle Giants who love flexing their considerable muscles; Armstrong's sister, Olivia also immediately gets along well with Sig's wife, Izumi, as both of them are Ladies of War with a propensity to demonstrate Good Is Not Nice.
 * A villainous example: Kimblee is the only human Pride and Envy seem to like, which says something about his morals (or lack thereof).
 * Ranma and Akane from Ranma 1/2 could be described as this. They're both stubborn, headstrong, competitive, short-tempered, forgiving, martial artists, etc. Whether those similar traits are the very things that attracted them to each other in the first place is up for debate.
 * Kyohei and Sunako from The Wallflower. In spite of their obvious surface differences (Kyohei is a devastatingly handsome Bishonen, Sunako a devastatingly creepy Strange Girl), they're actually a lot alike deep down. Both of them don't think too highly of surface beauty, have MAJOR issues with romance (much to the frustration of the other characters and readers), and Kyohei can even enjoy playing gory video games or watching horror movies with Sunako.
 * Lily and Terry in the Fatal Fury OAVs. Both are former street children who endured lots to survive in South Town.
 * This is the justification Ami in Toradora! offers for why she'd make a good couple with Ryuuji... Whether or not she's right is up for interpretation.
 * Kira Yamato and Lacus Clyne certainly qualify as this in that they are both idealists working for true peace. Anyone?
 * Garrod and Tiffa. However, they also qualify at the same time as Opposites Attract for their different attitude toward fate.
 * Setsuna and Princess Marina are a NON-romantic example of this.
 * Banagher and Audrey. One of the reasons why they bond quickly is the revelation that both spent the majority of their childhoods on the move. Audrey/Mineva and Riddhe develop this too when they both discover that they're trying to break away from the continuity of their respective families' past professions. Banagher also develops this later with Marida when they find out that they're both Cyber-Newtypes.
 * Except that Banagher ISN'T a Cyber-Newtype at all, he's a perfectly natural one. All Marida said was that they might not be that different, after all Banagher saw inside of Marida and saw that her life was full of sadness (She survived the first Neo Zeon war only to be prostituted and subjected to constant abuse and abortions, until Suberoa saved her). It's more than likely that Marida saw similar trauma in Banagher's life (Thus far the anime suggested, he was taken away from his father when he was young and then his mother died and left him alone). Nothing in the anime has suggested that Banagher is a cyber-newtype and in fact
 * Heero and Trowa are another non-romantic version (no matter what some Yaoi Fangirls say -- 'sides, Heero seems to ship Trowa with their common friend Quatre instead), thanks to extremely similar backgrounds.
 * Both Konata and Kagami have remarked about the similarities between the members of their little group of friends. Kagami even notices that her friends from her actual class (Ayano and Misao) are similar in some ways to her sister Tsukasa and their friend Konata. And of course, the otaku set, Konata, Patty, and Hiyori, seem to hang out a bit.
 * Kagami's comment also lampshades this series' Geodesic Cast.
 * Isaac and Miria in Baccano. Both harmless robbers with a staggering lack of common sense.
 * Erika and Walker in Durarara
 * Hei and Kirihara of Darker Than Black are both Big Eater stoics with a good heart who care about their teammates. Kirihara and November 11 both share a loyalty to teammates and a hatred of smoking, although November 11 is more... vehement about the latter.
 * Shiki and Rima from Vampire Knight.
 * Near the end of Neon Genesis Evangelion, a fair bit of time is devoted to showing how both Shinji and Asuka have the same sense of abandonment and need to be acknowledged, but react in different ways.
 * In Virgin Love, the two leads' Ethical Slut Work Hard, Play Hard personalities and their ablility to relate over work is what draws them together. Daigo describes it as finally having found someone who can meet him on the same level. They also both share the weakness of Pride.
 * Although they used their similar backgrounds to create different character traits, Hinagiku and Hayate of Hayate the Combat Butler have the similar pasts to make themselves candidates for this trope.
 * Recently, Luca has been added to these two, with a similar past, and adds more than a little of Hayate's looks to seal the deal.
 * Kotetsu Kaburagi and Tomoe Amamiya from Tiger and Bunny became friends upon discovering they were both superhero geeks.
 * Mahou Sensei Negima: (Possibly) one-sided version with Negi and Nodoka: both are quiet, unassuming, intelligent, easily flustered Cute Bookworms. They are also two of the most dangerous members of Ala Rubra, with unexpected but increasingly obvious Badass sides.
 * In Saint Beast, this is almost literal with Rey and Luca who are brought together by their ability to fly.
 * In Claudine, the main character and the local Hot Librarian Cecilia were united by their love of reading and poetry.

Comics

 * This was a recurring theme in the first issue of Heroes, Anonymous, where former sidekick Attaboy's struggles to make it as a solo hero are helped when he discovers a kindred spirit, Lynn, who eventually becomes his girlfriend as they bond over an old sitcom from the 80s, "Birds of a Feather." Except Lynn is easily the quirkiest living being on the planet (she's absolutely obsessed with Birds of a Feather and the only music she listens to is whale songs), while Attaboy's attitude is something along the lines of I Coulda Been a Contender.
 * Scott Pilgrim and Ramona Flowers have many of the same flaws, such as not being totally decent to their past loves. It comes to a head in volume 6, when Ramona tells Scott what she did during their separation -- exactly what Scott did: dicking around, watching reruns, and sleeping. Scott's friends declare them the perfect couple.

Film

 * James Bond and many Bond Girls are like this. Both being suave, sexy, seductive, and many times, they share the same occupation and goal.
 * This is the same for the novels to a degree. One reason Bond falls for Vesper Lynd in Casino Royale is that he finds her easy to talk to and open up to, and they find they have a lot to talk about.
 * John Le Carre's conception of Bond adds another element to this. Le Carre disliked Bond and said he's perfect traitor material (being that he actually worked in MI 6 he'd probably know), Vesper is in fact a traitor.
 * Both couples in White Christmas, the mature Bob and Betty in contrast to the outgoing Phil and Judy.
 * In Amelie, both Amelie and Nino are quiet little oddballs who are very kind but aren't all that good at making friends.

Literature
"They had both been put on the table where they stood and, having been placed there, they had become engaged because they suited each other exactly. Both were young, both were made of the same porcelain, and neither could stand a shock."
 * This goes at least as far back as Pride and Prejudice.
 * In Sense and Sensibility, Marianne acknowledges Edward is suited for Elinor because of this trope, although having a reserved lover like Edward would disappoint Marianne herself, who longs for someone who shares her taste in music and art; Colonel Brandon's Establishing Character Moment happens to include a Meaningful Echo of her words.
 * Fanny and Edmund in Mansfield Park, due to growing up Like Brother and Sister.
 * Bookworms Catherine Morland and Henry Tilney of Northanger Abbey... in conclusion, Jane Austen loves this trope.
 * This is a significant theme in Gone with the Wind. Scarlett spends the majority of the novel lusting after Ashley, who is different from her in every way that counts. Even though a bunch of characters, most often her father, tell her that like needs to marry like it takes her until the end of the novel to figure out she would be happiest with roguish Rhett Butler. Of course, by the time she clues in, he's sick of her.
 * Good Omens: Anathema Device and Newton Pulsifer have both given their vehicles names (hippy Anathema's is a bike; loser Newton's is the worst car ever). They're literally destined to hook up.
 * Harry Potter and Ginny Weasley are this way, both being fierce, Quidditch-loving Leos, with a darker sense of humor. This is in contrast to Ron/Hermione, who are Opposites Attract.
 * Neville and Hannah Abbott, whom JKR states he ends up marrying. Although this strikes many fans as an Ass Pull, on closer examination it's really not; Hannah has been stated multiple times to share Neville's interest in Herbology, and was a staunch member of Dumbledore's Army from the very beginning, meaning they have undoubtedly spent a great deal of time together off-screen and have quite a bit in common.
 * In The Hellfire Club by Peter Straub, this is the reason why villainous Serial Killer Dick Dart claims he loves and adores Nora. Because of a misunderstanding on his part where he thought she had kidnapped a woman and tortured her horribly for several days, he comes to believe that they are alike. He even comes out and says that he's so happy he found a female version of himself. In wit and many other ways, they are shown to be a worthy match... the only thing is that Nora is not fond of killing people in bloody ways.
 * In Andersen's The Shepherdess and the Chimney-sweep, the titular Star-Crossed Lovers are like this:


 * In Death: Winnie and Moriarity from Indulgence In Death are very much this. In fact, one woman says that those two are not two sides of the same coin, but they are the same side!
 * Audrey Wait: Audrey and James are huge music enthusiasts, and this is their go-to conversation topic.

Live Action Television

 * In the first season of How I Met Your Mother, Barney tries to seduce Robin, saying that "we both think commitment's a drag, we want something fun and casual, and we clearly get along". They didn't get together then, but jump to season four, where they're firmly in Will They or Won't They? Land...
 * Chuck and Blair on Gossip Girl are basically a male and female version of the same character.
 * In a completely different way, Blair and Dan.
 * Topher and Bennett of Dollhouse serve pretty much the exact same function in their respective houses.
 * Grimm: Some of the Wesen are this.
 * The Jägerbär (Bear) family for example.
 * The Spinnetod (Spider) husband and wife. According to the husband when they saw eachother in school "they just knew"
 * Wouldn't that be more like Love At First Sight?
 * It can be that AND Birds of a Feather. They recognized eachother's species and presumably began to date as a result of having that much in common.
 * Blutbad too. Granted with the wolf like nature of their species it is safe to say it is similar to how pack mentality works. It's natural for them to gravitate toward one another as in the case of Monroe, Angelina, Hap and Rolf.
 * Ironically despite being from different "species" of wesen, Rosalee and Monroe seem to be heading in this direction themselves. Both appear to have calm collected dispositions. Both are rehabilitated and are attempting to live normal lives. It would also appear that like Monroe, Rosalee has no qualms about doing mundane tasks like maintaining a herbal shop.
 * Seth and Anna on The OC were this - it ended up being the cause for their break-up.
 * Wendy and Tyler in The Middleman are both geeky artists with a high potential for heroics (even if Wendy was the one eventually chosen for the job).
 * All of the good, long lasting couples on The Office. These include Jim and Pam, Michael and Holly, Andy and Erin, and Kelly and Ryan (in later seasons that is, after he Took a Level In Jerkass) along with secondary couples like Bob Vance and Phyllis.
 * Carly and Freddie on iCarly, especially when compared to the other member of their Power Trio, Sam. Most notable in iSell Penny Tee's with the contrasting styles in running their t-shirt factories. Sam runs her 'factory' like a child labour sweatshop, while Carly and Freddie run their way by being nice and fun.
 * Jack O'Neill did poke fun of it in an episode of Stargate SG-1. "It has to do with flocking... and togetherness."
 * Birds Of A Feather is also the title of a BBC Britcom from the late 1990s.
 * The Doctor from Doctor Who has this relationship with both The Master and River Song. Ironically, this causes him to dislike them, rather than like them, although River does grow on him.
 * As of The Doctor's Wife we can add the TARDIS to the list.
 * Tate and Violet from American Horror Story, two Nightmare Fetishist emo teens. The two bond over cutting themselves.
 * John Sheridan and Ambassador Delenn from Babylon 5, whose interest in each other quickly begins to heat up when they discover that they share not only a gift for military and political strategy, but an innate curiosity about other races.
 * After Faith returns in Buffy the Vampire Slayer she sneaks off for a smoke, where she is found by Spike. Sharing the cigarette they discuss the potential slayers that are being trained up, going evil and Buffy. Their shared experiences (as well as a rather saucy comment Faith made while pretending to be Buffy that Spike had not forgotten) leads to a mutual understanding, respect and likeness for each other.

Video Games
"Shepard: This won't work, Miranda. We're too much alike."
 * Commander Shepard and Miranda Lawson in Mass Effect 2. Shepard comes this close to naming the trope if you decide to break up with her.

"Fiora: I am Fiora, the pegasus knight. You have been looking after my sister. Allow me to thank you.
 * Fire Emblem often gives support conversations and/or common endings at A support level to people who are very similar in personalities. I.e., we have the cavalier Kent and the pegasus knight Fiora: both are serious, protective, kind Lawful Good characters who bond over their similarities:

Kent: Oh, yes... When we were in Caelin, Florina spoke of you often...

Fiora: Oh, what did she say?

Kent: That you...were a lot like me."

Web Comics

 * Piro and Kimiko in Megatokyo.
 * Dora and Marten in Questionable Content.
 * Aubrey and Jason in Something Positive.
 * Joyce and Walkerton in Its Walky.
 * Abbey and Daisy in Bittersweet Candy Bowl - at least to a certain extent.
 * Yun-lee and Dong-whi in Nineteen Twenty One who are both mad about cats and looking after the local strays.

Web Original

 * Tris and Chaos (two wacky outlaws), Beth and Corri (two extremely good Jedi), and Moira and Darth Apparatus (two insane Sith) in The Gungan Council.

Western Animation

 * Jack and Maddie in Danny Phantom. True, one is closer to Earth then the other (three guesses on who the obvious culprit is), but they both share a mad obsessive love for hunting/researching the paranormal field of ghosts.
 * In Happy Tree Friends, Cuddles and Giggles both love the color pink, and both are really nice characters with hidden depths (Cuddles is rather rebellious, and Giggles gets pissed at polluters.) Plus, even for Happy Tree Friends, they die a lot.
 * On the Total Drama series, Gwen and Duncan become close after they discover that they share several interests in common. While they insist that they're Just Friends, their respected partners get incredible hostile over it, resulting in.
 * This seems to be the case with Sierra and Izzy as well.
 * Zuko and Mai of Avatar: The Last Airbender somehow manage to be this and Opposites Attract at the same time. While they're both perpetually frowning Emo Teens with some kind of family issue who are from the Fire Nation and use bladed weapons, their temperaments are completely opposite: Zuko is a Hot-Blooded Determinator, whereas Mai is an emotionless Defrosting Ice Queen.
 * Zuko and Katara are arguably a non-romantic example of this. Both are passionate, determined individuals willing to do whatever it takes to accomplish their goals, whether it be capturing the Avatar or helping him. Both are also shown to be pretty evenly matched in terms of bending abilities, and the few times they are actually on the same side/not angry at each other they work very well together and get along extremely well, showcased best in the finale.
 * Kick and Scarlet Rosetti in Kick Buttowski.
 * While they never got together, and firmly remain as Just Friends, this is the most likely reason for why Rogue was attracted to Scott in X-Men: Evolution. Both have dangerous, uncontrollable powers, both lived sheltered lives, and have an older sibling like dynamic with younger students.
 * Finn and Marceline from Adventure Time, who both enjoy adventure and edgy lives.
 * In Episode 5 of The Legend of Korra, Bolin explains to his brother Mako why he likes Avatar Korra: "Korra and I are perfect for each other. She's strong, I'm strong. She's fun, I'm fun. She's beautiful...I'm gorgeous!"

Other

 * Occasionally offered as one reason behind Unknowing Incest situations. This reasoning is referenced in "Weird Al" Yankovic's "A Complicated Song": "I was / Feelin' pretty down / 'Til my / Girlfriend came around / We're just / So alike in every way, I gotta say..."

Real Life

 * There may be some real-life basis to this as it's better in the long term to have someone who shares similar values to you when you get to things like kids, money, religon ect.