Chosen Family

Chosen Family is the trope where characters who start out as strangers start their relationship as friends but then grow to the point that their bonds are like family. While these people may have their biological families, these friends can fulfill the role. In some cases, the characters might have something happen to their family, such as being separated or dying. In addition, there are some examples where a family would disown their members for whatever reason. These causes can leave an empty place in a character's life and may even traumatize them. However, they can develop not only a relationship but also as a person. This trope can happen due to many adventures, in the workplace, or just trying to save the world. While many circumstances can lead to this, the one thing for sure is that the bonds made from a Chosen Family cannot be easily broken.

See also Fire-Forged Friends and True Companions.

Examples of Chosen Family include:

Anime and Manga

One Piece: As pictured above', the Straw Hats are a crew of pirates led by Monkey D. Luffy where he refers to them as his nakama. Each of them had lost a family member early in life while also carrying a dream they wanted to accomplish. Yet, despite their diverse backgrounds, they come together in an intimate way that they can work as a team in many situations.
Romantic Killer: It's revealed that Riri, rather than creating an Unwanted Harem for Anzu as was his directive, established this instead. Kazuki needed friends to help him recover from his trauma with a violent stalker named Yukasa, who went as far as to drug and dox him. While his father showed No Sympathy, his mother and sister decided to send him away for his safety, with Anissa regularly checking in on him. Anzu is the first girl that didn't trigger Kazuki's trauma, and he finds himself happy for the first time when living with her and Junta. Junta doesn't have any hang-ups, but he is insecure about how Anzu has never noticed his feelings for him since he used to be chubby "Tonta". While Hijiri doesn't come to live with them since he's wealthy, attending a normal school and working retail with Anzu tempers his narcissism, and he comes to respect how Anzu doesn't want his money or good looks. And Riri, for better or for worse, learns more about humans and breaks the rules to protect Anzu and Kazuki from Yukasa.
Sailor Moon
- Each season shows numerous times that the Inner Senshi, along with Mamoru and the cats, have become a true family. Mamoru and Makoto are orphans, Ami rarely sees her mother due to the latter being a busy doctor, Minako ran away from home in the manga to become a Senshi on realizing she had to fulfill her duties while in the anime they never show up, and Rei is estranged from her father and she keeps her grandfather at an arm's length in the manga due to her trauma while being overprotective of him in the anime. Usagi is the only one whose Good Parents are together and alive, but it's confirmed she needs her friends as her trauma accumulates over the seasons. Indeed, it's her friends nearly dying again that causes her to have her R upgrade, as it snaps her out of her Heroic BSOD about being forcibly reawakened.
- The Outer Senshi also become this in the manga and the anime when they adopt Hotaru, who has reverted to baby form. Haruka and Michiru have taken over raising her, as it's unexplained in the anime what happened to Professor Tomoe who survived the events of the story and was confirmed to be brainwashed by the real Big Bads, Pharaoh 90 and Mistress Nine. What makes this an eventual tearjerker is that in Stars, Haruka and Michiru attempt to become Fake Defectors in an attempt to stop Galaxia, and "prove" their loyalty by killing Setsuna and Hotaru.

Comic Books

Runaways have the titular group of teenagers realizing their parents are supervillains and running away to oppose their evil lifestyle. They all come together not only as a superhero group but also as a functioning family. Alex was the exception, using the other kids to save his parents from being stabbed in the back; Nico doesn't take it well, whacking him in the face with her staff when he offers We Can Rule Together. Molly also hasn't forgiven Alex long after he died for his failure. Indeed, the first arc ends with Captain America finding the kids after they escaped their parents and sending them to foster care, but they all run away to reunite, realizing they Can't Stay Normal. The Rainbow Rowell arc goes as far as to have Molly suggest that Nico use magic to become the other kids' legal guardians rather than run away from foster care on a regular basis.

Fan Works

By the end of the fourth chapter of the Sailor Moon fan fic Isekai by Moonlight, many of the Sailor Senshi considered themselves to be closer than siblings — to the point that the characters who had no living parents were either informally or officially adopted into Sailor Mercury's family.
In the story Inter-Library Loan by Phouka -- part of a Mega Crossover series revolving around the Buffy the Vampire Slayer characters re-settling in Cleveland after the end of the series -- Xander explains to Winky the house elf how the Scoobies are all family who chose each other:

“But ...” and Winky's brow puckered. “Master Xander is not father. Neither is Master Giles or Master Jarod. Mistress Willow is not mother. Mistress Jenny is mother, but . . . not? Mistress Dawn and Mistress Buffy are sisters, but Master Xander and Mistress Willow are not. Winky is confused.”
“Ah,” Xander said. “Okay, let me do a little explaining, Winky.”
She gazed up at him in complete trust.
“Some of us, like Dawn and Buffy, are lucky enough to be related by blood, and everybody calls that family. That kind of family, sometimes it works and sometimes it doesn't. Buffy and Dawn's family worked, but their mother died, and they were all alone.
“Some of us, like me and Jenny, don't have anyone around who is related to us by blood. So we don't have any family that way. What we do have is some very good friends, friends like Master Giles and Mistress Poppins and Mistress Willow and Mistresses Buffy and Dawn. They are such good friends, and there is so much love, that I say they are my family. Master Giles should have been my father. Mistress Jenny is like my favorite aunt. Mistress Buffy is practically my sister. Does that make sense?”
Winky was overwhelmed with thought for a long moment.
“Master Xander, does anyone ever stop being family?”
He took a deep breath. “Well, I won't say it's never happened, but they would have to try really, really, really hard. And we'd probably still say they were family.”
“And Winky gets to be with Master Xander's family?” she asked.
“Forever and a day.”

The Family from the Worm/Luna Varga crossover fic Taylor Varga. Whether they're in their lizard guise or not, Taylor Hebert, Amy Dallon and Lisa Wilbourn have effectively formed a family unit without actively thinking about it, mostly as an outgrowth of masquerading as cousins in lizard form.

Film

Over the Hedge has a group of different woodland animals that act like a family and even consist of two biological families that are a part of the group (the opossum and porcupine families).

Literature

The regulars from the Callahan's Crosstime Saloon stories. Starting with Tom Hauptman, a preacher who lost his faith when his wife died who found a new family among the bar's regulars, most of the regulars are as close as family by the climactic story.

Live-Action TV

The Kamen Rider Club are teenagers from different high school groups uniting to help Gentaro Kisaragi, aka Kamen Rider Fourze, fight the Zodiarts. While each member had some conflict, they joined the group, overcame their hang-ups, and assisted the Kamen Rider's fight.
Technically, the main characters in Angel run a business called Angel Investigations, which is Cordelia's idea so they can pay rent while she waits for her big acting break. Seasons one and two, however, make it very clear that Angel needs them to stay grounded and tethered to his humanity, no matter what Los Angeles as well as Wolfram & Hart toss at him. Doyle, a former criminal and demon, used his last moments to save Angel and Cordelia while passing on his gifts to the latter. Wesley finds a new home after the Watchers fire him, and he goes off the deep end when his attempts to save Angel's son lead to Connor being kidnapped instead, and Angel tries murdering him in revenge. It's also because of Angel and Cordelia's machinations that they rescue Fred from another dimension, create an Alternate Timeline where Connor has none of the trauma that came from Holt kidnapping him as a baby. Cordelia finds her purpose, Lorne uses his musical skills for good, Gunn puts his monster hunting skills to use, and Fred regains her sanity.
In Buffy the Vampire Slayer, the Scoobies have become this, to the point where two of them become a Parental Substitute duo to Dawn, who is the only minor left in the group by season six. While Buffy started hanging with Willow and Xander after they learned about vampires and decided to do what they could to help, Cordelia joined the group under protest after supernatural forces killed one of her boyfriends and started targeting her on a regular basis.
The Nine-Nine are this in Brooklyn Nine-Nine. While they were close-knit before Holt joins the team, Holt does help shape Jake up and admit that his team is the best family he has. Out of the characters, Terry is the only one that has a stable home life with a wife and losing daughters; Rosa doesn't get along with the cheerful side of her family, Amy constantly competes with her brothers to get her mother's affection, Gina is only close with her dramatic mother, Boyle loves his extended brood but suffers a lot of angst when it comes to his ex-wife and later pursuits of women, and Hitchcock and Scully only have each other, with the Nine-Nine unsure if someone named Kelly is Scully's wife or dog. (Scully reveals in season seven that his wife and dog are both named Kelly.) Holt and his husband Kevin also become mellower after he joins the Nine-Nine, especially when they surprise the couple with an anniversary dinner.

Puppet Shows

The Muppets franchise is all about this:
- The Muppet Movie is about Kermit setting off to Hollywood to become rich and famous. Along the way he acquires friends in Fozzie, Gonzo, Miss Piggy, and all the main Muppet cast. As he tells Doc Hopper, he found a family because they share the same dream.
- Muppet Treasure Island has Gonzo and Rizzo tell Jim that they are his family. Even if they don't look like each other and are different species, they are brothers.
In Sesame Street, it's shown that the whole neighborhood can become your family if you let them. The adults comfort Big Bird and promise to take care of him after he finds out that Mr. Hooper died.
- The film Follow That Bird has a social worker convinced that Big Bird should live with an actual bird family. Big Bird is so miserable that he runs away, and the movie is about the Sesame Street gang coming to rescue him.

Video Games

The Phantom Thieves of Hearts from Persona 5 are a group that rebels against the adults who deceive, hypocrisies, and corrupt society by stealing their hearts. Each member consists of teens who have been wronged by adults throughout their life and awakened to Persona. Most of their peers see each of them as misfits, but they find solace with each other and become great friends.

Western Animation

In DuckTales (2017), Clan McDuck consists of not only Scrooge McDuck and the Duck Family but also their friends who became a part of their group. Even though "duck" is in their name, some aren't ducks, such as supernatural creatures, scientists, aliens, robots, etc.
Luz Noceda becomes part of The Owl House by apprenticing to Eda Clawthorne as witch and living with the little king of Demons, King. Thanks to Luz's influence, Eda and King soften to her and even gain a familial bond. Lilith, Eda's sister, even considers herself to be the aunt of their family. Even King is inspired to legally change his name to King Clawthorne.
- Vee, a shapeshifting basilisk, took on Luz's identity when she came to the Boiling Isles and was adopted by Camilla Noceda after her identity was revealed. In the season 3 premiere, when Gus, Willow, Hunter, and Amity become stranded in the Human Realm, the witches and Grimwalker become a family over the months. It even made Hunter cry when Luz declared it to him.
The Best Friends Squad in She-Ra and the Princesses of Power, By the show's end, Adora has no interest in finding her birth family anymore. She already has a family.
Superman: The first episode of the Superman Family Album ("The Adoption") has this as a plot point. While several other couples show an interest in adopting the baby Kal-El, he settles the matter by flying over to an open window in the Kent farmhouse and settling in with Martha and Jonathan Kent. The rest is history.
In Voltron: Legendary Defender, the Paladins and Allura start as a borderline Ragtag Bunch of Misfits and end up becoming this through Character Development.
Avatar: The Last Airbender has this for the Gaang: we have an orphan Airbender that realizes he lost his family a hundred years ago, two Water tribe members that lost their mother while having a father at war, a runaway Earth Kingdom noble that hates her family limiting her, and later on, a Kyoshi Warrior leader with her fellow Warriors imprisoned and separated.