Magellan: Hello, I'm Magellan, a traveling mage. I notice your group has no wizard.
Rogar: You seem trustworthy. Would you care to join us in our noble quest?
Magellan: Yes. Yes I would.
When a new character permanently joins an ensemble cast, it takes an astonishingly short time for them to get to the same level of rapport with the other characters as they already had with each other (and with the character they're replacing). Expect one Fish out of Water episode, and then they'll be flirting, sharing intimate secrets, in on all the jokes. Can overlap conceptually with Replacement Goldfish, when the new "fish" is immediately treated and acts as a beloved friend.
In an action series or a video game, they'll be willing to die for everyone else, and vice versa, with a passion nobody ever shows for the one-episode Millstone character. Of course, the outsider status could be resurrected for a one-episode conflict later, or they could turn out to be The Mole. (if so, and the character regrets their actions, they will be Easily Forgiven)
Especially jarring in HeelFace Turn scenarios.
- In Black Lagoon, Rock integrates rather quickly with the crew of the Lagoon, insofar he goes from being their hostage to being, at least superficially, "one of them" in the space of about a day, helped by the fact that he saves all of their asses by devising the most balls-to-the-wall insane method of killing an attack helicopter ever. Rock himself lampshades this at one point and starts to wonder if he's developed Stockholm Syndrome because of how calm he is over the degree of familiarity he gets with them so quickly. Revy is the exception: it takes her about six episodes to properly accept him once he has actually joined them.
- One of many reasons that Shirayuki Berii of Tokyo Mew Mew a la mode is marked as a Canon Sue. The True Companions are generally inclusive and friendly, but Berii makes them practically worship her before they even speak to her.
- This is a frequent occurrence with new members of the Strawhat Pirates in One Piece, although Luffy is the kind of guy who'd be quick to be friendly with anyone he meets unless they do something to get on his bad side. The only noticeable exception is Robin in how she never refers to any of her fellow crew mates by name until the end of the Enies Lobby Arc. It is implied that Luffy can somehow sense the true intentions of people he meets even if they act the other way (like Blackbeard on Jaya).
- This is the case in-character for Bakura in the Monster World arc of Yu-Gi-Oh!. Although Bakura has met Yugi and the gang before, his White Wizard character piece on a tabletop RPG has not. The White Wizard readily joins the players' party and tries to sacrifice his life for them all within a few turns.
- Even worse in LARP than in RPGs, as the "new guy" is remarkable similar to the recently lost one. Possibly because it's the same player with a different costume (and not always). Worth noting that when players try to play it straight and to build a new relation from zero, it staggers the game a lot, and often kills it outright. In that case, for LARP games, this is an Acceptable Break from Reality
- David from Animorphs could almost be considered a deconstruction of this; the Animorphs (except Marco and Ax) expect a relative stranger to join their team, cooperate with them, and go along with their tactics. However, the Animorphs play their hand poorly, and David is a bit too selfish for their tastes. It doesn't end well.
- Played for drama in The Mysterious Island. When the colonists recover Ayrton from the Isle of Tabor, they're all too happy to welcome him into the team, thinking he's a shipwreck survivor just like them, and are surprised when he initially distances himself from them and prefers to be left alone. Of course, they don't know that Ayrton is burdened by his past misdeeds as a former mutineer and pirate, originally marooned on the island as punishment at the end of In Search of the Castaways. Later, however, Ayrton warms up to the colonists after helping them defeat his old pirate crewmates.
- Oliver in Coupling. Goes on a blind date with one of the main characters and it doesn't work out. In subsequent episodes he gets involved in the six-way phone call, and Jane later invites him to Sally's dinner party and Susan's antenatal class. By his fifth episode he's having regular drinks with Steve and Patrick, in Jeff's old seat.
- This trope is also employed in the second episode, when Patrick befriends then-strangers Steve and Jeff, although Jane takes until the third episode to make friends with Susan. Played straighter with Jane and Sally, though.
- Averted in Farscape. The original cast takes most of the first season to warm up to each other, new characters are in for a rough time until they prove themselves, and some (notably, Sikozu) never quite get the all-around seal of approval.
- Rachel in Friends, although she does have some prior connections.
- Game of Thrones: Davos with Jon Snow, who he becomes staunchly supportive of after Stannis is killed, despite prior interactions being limited and not overly friendly.
- Will in The Inbetweeners. This may be due to British Brevity preventing any sort of drawn-out character arc.
- Stargate SG-1's introduction of Teal'c, in which he betrays his god in a HeelFace Turn, makes it seem odd that O'Neill trusts him so quickly, to the point of sternly insisting on his inclusion into SG-1. Jonas Quinn averted it, however.
- Averted in Stargate Atlantis when Ronon was added to the cast as a replacement. It takes Ronon a few episodes to become comfortable with the team and start forming deep relationships with them. (A dead girlfriend and several years of being unable to stay in any one place for very long without endangering lives will do that to you.) He definitely takes a little longer to mesh with the team than most examples on this page, but they're all pretty tight fairly quickly.
- Robin in How I Met Your Mother mainly due to Ted's instant interest in her in the series' pilot.
- Common in Power Rangers, each time one of the rangers is replaced. Or each time the rangers meet someone who's not obviously a Monster of the Week.
- All the Maquis characters in Star Trek: Voyager. By half way through the first season (once they get rid of Seska), none of the Starfleet personnel seem to care they're working with terrorists, and none of the Maquis seem to remember that they believe Starfleet and the Federation sold them down the river. Granted, they've got more important things to worry about, but still, you'd think it rated an occasional mention.
- It got Lampshaded when they finally established contact with Star Fleet, when it turned out that their superiors had been extremely concerned about it, while they had mostly just forgot about it.
- And it was referenced in the episode Worst Case Scenario, which centered around a training program based on the idea of a Maquis rebellion. Seska was involved in that one, too, despite being dead.
- There was another episode when Tuvok had to deal with some discipline problems among low-ranking Maquis. When they complained to Chakotay that they prefer the Maquis way, he punches one of them in the face and tells them to go give the Starfleet way another try. By the end of the episode, they all trust Tuvok and he trusts them.
- For that matter, the crew accepts Neelix, Kes, and even Seven remarkably quickly, considering two of them were strangers from previously unknown alien races and the third was an enemy combatant. Neelix's first act was actually to use their help under false pretenses to rescue Kes.
- One episode after B.J. was introduced in M*A*S*H, he was inexplicably Hawkeye's best bud and the incoming Colonel Potter, looking over their records, berated them for how much goofing off they did together. This after B.J. had been introduced as a straight arrow in the previous episode. One has to wonder if the episode was written before Wayne Rogers left and they just crossed out "Trapper" and wrote in "B.J." without changing anything else. According to a "behind the scenes" show on the Biography Channel, this is exactly what they did.
- This happens in season 3 of after the character of Caitlin Todd is killed off, her replacement is Mossad Officer Ziva David, who joins the team only a couple of episodes after her half-brother (the terrorist Ari Haswari) murdered Caitlin. However, this could be seen as an aversion, since they show the other members of the team being fairly open to her, but commenting on how it is odd for their boss, Agent Gibbs, to do the same. This is explained as Ziva having saved Gibbs' life when Ari came to kill him in his basement (by shooting her half-brother), forming a bond of trust that otherwise would not have occurred nearly as fast.
- And again with Eleanor Bishop, who joins the team after Ziva leaves, following the death of her father and subsequent revenge. Every member of the Team Gibbs takes to her very quickly, including Gibbs himself (justified, as he was suffering a minor Heroic BSoD at the time, and was thus more vulnerable). Of particular note, is Tony Dinozzo who took Ziva's departure harder than anyone, but still was just as welcoming to Ellie as all the others. Interesting in that Ellie actually realizes this, and is rather upset that everyone is going so easy on her.
- H.G. Wells in the last episodes of season two on Warehouse 13. She joins the team suddenly in one episode, treated as family the next, before she betrays them in the season finale.
- Averted in Dead Like Me with Daisy. It takes the rest of the reapers quite a while to get used to her.
- In pro-wrestling, Heels are generally friends with Heels, Faces with Faces. When a Face turns Heel, it is often quite strange, as they become friends with wrestlers who have attempted to do various despicable things to them in the past. On one memorable occasion, Stone Cold Steve Austin turned heel and teamed up with Triple H... who had previously ordered Stone Cold to be run down, in an attempt to end his career or kill him. Often the whole thing comes with copious amounts of Lampshade Hanging, whether immediately (the "I don't like you and you don't like me, but let's team against our common enemies" speech) or down the road as a Continuity Nod (witness the interview with Triple H's team at Survivor Series 2007, where Kane and Jeff Hardy call in their receipts for the various heinous behaviors that HHH has subjected them to over the years when he was a heel).
- Common in tabletop RPGs when a PC gets killed and the player has to make a replacement character.
- Pick a role-playing game that doesn't involve the player creating the entire party from the start. Odds are, this trope will show up in it at least once.
- Tales of Symphonia was particularly bad about this. Sheena fights the group twice before joining up and just a few scenes later she's giving advice to Colette (which she takes to heart). Then you have characters like Zelos and Presea who they just meet, but are already talking to as if they are "one of the guys."
- Though Lloyd does spend about... Ten minutes somewhat miffed over the level of familiarity Zelos presumes with the rest of the party. After which he seems to have resigned himself to it — Zelos is, to put it mildly, easygoing. Presea never really integrates until her exsphere is brought under control, at which point the party are already well familiar with her.
- And, uh... this IS Colette we're talking about. She would have taken advice from Sheena to heart if the woman was still actively trying to kill her!
- Not to mention that, even as Sheena was trying to kill her, Colette was more then happy to try to make friends with her and held her in high regard (see: pre-battle conversations and post-battle Z-skits). The speed at which the rest of the party accepted here tended to be a bit more reasonable, though by the time they reached the Tower of Salvation (either very soon after Sheena joined or quite a time later depending on which route you took), even Raine was willing to trust her. (see: No real questions about her summoning skill and everyone trusting her information about getting to Tethe'alla)
- Fire Emblem. This happens so much, it is a wonder that the hero's group doesn't pick up any spies. Reports are, the only spies in the series (Nasir and Orson) are the few characters that don't meet the heroes this way.
- Justified in Shadow Dragon; the people you recruit from the enemy are either conscripts forced to fight against you (and thus willing to join you given even the vaguest excuse), prisoners (who have no reason to bite the hand that saved them), or friends/family of the people who recruit them (who have someone to vouch for their trustworthiness). The people who join you without being recruited, meanwhile, were either hired by people backing the heroes or Fire-Forged Friends.
- Played quite straight in Yggdra Union: We'll Never Fight Alone, except the joining enemy was trying to kill you for 26 maps, and it takes less than 1 map to try and risk the male lead's life to save her. Either they're too confident, or too idiotic.
- On that note, she's probably the only one who actually makes any attempt to prove her trustworthiness. Everyone else is all, "Okay, we trust you already, stop trying so hard." Oh, and don't forget Russell, although he had an excuse, he was only fighting for the Empire because Gulcasa was holding his fiance hostage.
- Happens a lot in Exit Fate, as the game has 75 recruitable party members.
- Petra just joins the army because she doesn't think you respect a woman's strength. Shin is almost literally an incarnation of evil and tried to turn Soth into something similar and you have to fight them, but then Soth joins up to redeem himself and Shin joins because you seem interesting. The vampire Vanrushal takes the cake though — after you and the exorcist Luther confront and fight him in his evil mansion (after killing dozens of evil minions) he claims that he's weakened down to near-human levels and can't stay here, so he joins your army. Without your approval. Against Luther's loud protests. (Luther joins too, to keep an eye on Vanrushal.) Granted, as Vanrushal points out, he was keeping to himself and it was your party that tried to kill him, and he wasn't even an evil vampire — Luther's just a (fairly benign) zealot when it comes to vampire hunting.
- Implied by the way the Relationship Values work in the game — while some characters are obviously friends with each other from onscreen interaction, other characters instantly gain a relationship bonus with other characters offscreen. Why a cat and a dog are friends with each other, and why two Cool Old Guys happen to be buddies, is completely up to speculation.
- In Final Fantasy VII, when Shinra seems to know where you're headed after the Gold Saucer, Cloud has a scene where he forcefully refuses to consider that anyone on his party could be a traitor, saying that he doesn't want to suspect any of his friends. Keep in mind that you just met Cait Sith five minutes ago, and he's only known Aeris and Rex XIII for a week at most. It's possible to literally have met Yuffie thirty seconds before this cutscene happens. And while Cloud has bonded rapidly with Aeris, Yuffie and Cait Sith's initial introduction to the party don't involve any sort of bonding — they basically elbow their way in even though it's clear nobody likes them. Cloud's insistence that they're all his close friends becomes extra-hilarious when you consider the fact that Cait Sith is, in fact, the traitor in question, while Yuffie is a thief out to take them for all they're worth.
- Subverted in Wings of Liberty: Matt Horner and Tychus Findlay continuously clash with each other throughout the game, as the former has been Raynor's Lancer for four years and the latter his Big Guy best friend years ago before being thrown into prison. Raynor trusts both, but Matt was right: Tychus was only released from prison to get close to Raynor and kill Kerrigan.
- Brookes in Breakout - going from pretty much nobody to an integral member of the crew within all of about 10 minutes. Though the fact that he is pretty much The Chosen One does somewhat account for this
- The Trolls and Kids to each other, considering they've known each other for all of a day on positive terms, although the Trolls harassed them previously. Averted however with some of the Trolls who outright refuse or seem disinterested in getting to know the Kids somewhat justifiably given that they unleashed a Physical God on the Trolls who started killing them.
- Deconstructed in the case of John and Vriska — they show romantic interest in each other during the 24 hours of contact, but when they meet up again much later, it becomes apparent that it was never going to work out between them.
- Stand Still, Stay Silent: Inverted with Reynir. On his first morning with the crew, he gets sent back to bed half because he was disturbing Tuuri's work, half because he hadn't gotten much sleep the previous night. Soon after falling asleep, he stumbles upon Tuuri's older bother Onni via the mage Talking in Your Dreams system. Onni asks Reynir how Tuuri is doing when he finds out he's travelling with her, which causes Reynir to call himself "a lousy friend" for not having asked Tuuri (and at least one other person, as he used the word "them") how she's feeling about the expedition so far. The straighter version gets averted as the official crew had only existed as a group for only about two days when Reynir arrived, which made him an extra person to get used to having around for everyone else rather than an intruder in an established group of True Companions.
- Teen Titans:
- Terra meets the main cast in one episode, becomes best buds with them in a minute, then leaves in a fit of rage after (mistakenly) thinking they had betrayed her at the end of that same episode. Later, she comes back with a big smile on her face, offering her unending services to the team. They take her in, they throw her a big old welcome party (with the exception of Raven, who dryly tells Terra to help herself to the fridge and to make sure she cleans up after herself before she inevitably leaves), and then she attempts to murder them all. This is over-simplified; not only is the Plug 'n' Play Friends aspect ginormous here, Terra herself is actually very well developed as a character and the reasons for her actions are not hard to discern.
- Another episode has Blackfire, Starfire's older sister. Very jarring in that she compliments each character (except Starfire, obviously) and instantly has their friendship, even Raven. By acting buddy-buddy with Cyborg, laughing at Beastboy's jokes, noting Raven's forehead chakra, and flirting with Robin. Then she turns out to be a thief and tries to kill Starfire. Oops.
- Averted twice in Avatar: The Last Airbender:
- Aang welcomes Toph immediately, but he likes everyone. Sokka welcomes her as a powerful ally from the start, but doesn't seem to relate to her as a friend for some time. Katara, on the other hand, oscillates between obvious efforts to get closer to Toph and fighting with her well into the following season.
- When Zuko joins the Gaang, he is also not welcomed immediately. He needs a separate episode with each of Aang, Sokka, and Katara to get their acceptance and forgiveness. Sadly, no life-changing field trip with him for Toph.