Bob is a bit off. He might be a helpful member of the True Companions, but his habit of breaking into song and dance for no reason, or his obsession with rulers, or insisting that he carry a carrot of no less than 6.12 millimeters (and no longer) in length at all times, or saluting whenever the air temperature drops below... well, you get the idea. Put quite simply, he's hard for anyone to understand, talk to, or otherwise work with. Everyone except his (long suffering, but inexplicably loyal) friend Alice, that is.
In a nutshell, this trope is about someone who has the task (be it as a friend or their actual job) of keeping an eye on the resident Cloudcuckoolander, Fish out of Water or other strange person. They might be a close friend, relative, hired bodyguard or nanny or even just a plain old servant. As long as they accompany someone who's a bit crazy and try to prevent things getting out of hand, they're this trope.
Services this tour guide can provide include:
Generally keeping them out of trouble (calming down angry locals, posting bail, finding directions to the nearest stationery store or farmer's market, etc).
In BleachIse Nanao is in charge of a) getting the stupidly powerful Captain Kyouraku off his ass, because otherwise he'd be completely drunk all instead of just most of the time, and b) keeping her division from falling into (more) chaos.
It's more of Obfuscating Stupidity as Kyouraku is among the most observant and keen minded characters in the series. He's still quite lazy, though, so he really does need Nanao around.
It's implied that Lisa, his lieutenant before Ise, had a similar task keeping him in line, although she seemed to do it in a slightly different manner.
In Azumanga Daioh Chiyo-chan is one of these to Osaka. Particularly amusing since the former is much younger than the latter.
In GA Geijutsuka Art Design Class Mizubuchi is this to the art club president; Awara. She even lampshaded it once, noting that she has a friend who she always needs to take care of.
In Hayate the Combat Butler Sharna Alamgir was, according to the mangaka, created to play the Straight Man to Fumi Hibino's goofball character and basically exists to provide snappy comebacks. It must be a bit hard for her, since she is a foreign exchange student herself.
Even if Haruhi Suzumiya hadn't been a Reality Warper Kyon's life would have been a lot easier if he hadn't met the titular character to begin with. But instead he allowed himself to be forced into her self created club to search for aliens, time travelers, ESPers etc. and keep her entertained.
In Kill Me Baby Sonya is this to her classmate Yasuna Oribe, who's always coming up with new (and stupid) ideas. The problem being that Sonya also happens to be a short tempered, violent assassin...
In Axis Powers Hetalia, it's often left to poorGermany to look after the other members of the titular Axis powers. His hands are usually full with whatever idiocy Italy has gotten into, but he also does his best to get Japan into shape to face off against the Allies. China tries to be this for his many siblings, but one of their strange tendencies is is a general lack of respect for him (except for South Korea which is just...weird).
The main job of the strawhats (particularly Sanji, Nami, and Ussopp) seems to be acting as a CloudCuckooLander's Minder for the rest of the crew (mainly their captain Monkey D. Luffy).
In A Cruel God Reigns, Pascal often ends up being this for Marjorie, as he is the one that she lives with mixed with the fact that he is her older cousin. Nadia sometimes also fills this role.
In Transmetropolitan the Filthy Assistants - Channon Yarrow, an ex-stripper-nun turned bodyguard, and Yelena Rossini, a chain smoking would-be writer - are this to gonzo journalist Spider Jerusalem. Yes, they really are the sane ones.
Bob, Deadpool's CIA handler in Deadpool MAX. In addition to doing the parts of the job Deadpool is too insane to do and keeping Deadpool focused on the mission, Bob is essentially the only reason Deadpool is willing to do the job in the first place. In this continuity, Hydra is a figment of Deadpool's psychosis. Part of Bob's job is to exploit this by maintaining the facade that he's a former Hydra agent and the targets selected for Deadpool to assassinate are all high-ranking Hydra operatives.
Then there is Cable who often serves as Deadpool's minder in the reguar continuity.
From the same series, Finnick Odair could count as this to Annie.
Tamora Pierce seems fond of this trope. Daine needs to watch Numair, (despite his being the most powerful mage in Tortall), Nawat needs Aly to explain the inexplicable to him, and Qiom, who needs Fadal (well, Fadala) to do the same, what with his being a former tree. It's even worse with Qiom, as some of the instinctive things an animal would do don't come naturally to him. His Minder needs to make sure he doesn't burn himself eating food too soon, or getting hauled up at the local temple for something equally (but obviously more disastrously) stupid.
Jeeves to Bertie in Jeeves and Wooster. His mission in life is to make sure that the young master stays unmarried and out of trouble and doesn't leave the house wearing anything too ridiculous. For all his oddities, however, Bertie is fond of "the quiet life", and if anyone's the king of Zany Schemes, it's Jeeves. Bertie also sometimes plays this role for his crazier friends, Bingo Little in particular.
In Harry Potter, Ginny sometimes ends up as this for Luna - notably during Luna's first appearance, where Ginny convinces everyone that Luna's okay, just rather odd. Fits in, as Ginny was Luna's pretty much Only Friend.
While Harry Dresden isn't a Cloudcuckoolander, per se, from an outsider's perspective, he does come across as Ambiguously Autistic. He asks seemingly-random questions, makes odd requests, and somehow produces results out of nowhere. To the Chicago PD, Harry is quite an asset. To this end, Karrin Murphy fulfills this role to Dresden, as a Minder between the police and Dresden.
Live Action Television
In Fringe Peter, Olivia, and Astrid are this to Walter.
As befits their status as expies to Watson and Holmes, Dr. Wilson generally serves as this to Dr. House. Dr. Cuddy also served as one of these until leaving the show for the final season.
Sometimes, on Doctor Who, the companions are dragged into taking care of the Doctor! Generally restricted to Four and Eleven though.
In the Made-for-TV Movie in which Eight appeared, his companion actually tried to dispense with all this rubbish and have him put in the psych ward (mostly because he tried to tell her about the imminent The End of the World as We Know It, although acting like a lunatic probably didn't help his credibility any). She also explained away his odd behavior to strangers as a result of his being British.
The title character of the TV show Monk, who suffers from OCD, employs a helpful companion (Sharona in early seasons, then Natalie). She hands out sanitizing wipes, does all manner of dirty work, explains his odd mannerisms to others, and generally runs interference between him and the world.
In Glee, Santana sometimes functions as this for Brittany early on, but it's increasingly revealed that Brittany's actually mostly capable of taking care of herself, and their relationship becomes more equal over time.
On Father Ted, Ted had to try and keep a handle on Dougal, who had a sort of unique interpretation of reality.
Ted: (holding plastic toy cows) These are small. But the ones out there are far away.
On Leverage, Sophie often serves as a minder for Parker, usually by giving her advice on how to survive in social situations and act like a normal person while trying to pull off a con.
Although all the team members become Cloudcuckoolander minders for Parker at one point or another.
John to Sherlock on Sherlock, even more so than the original Watson. He spends a lot of time apologizing for Sherlock or translating his behavior.
Sherlock:(Accepting present from client, without unwrapping it) Diamond cuff-links. All my cuffs have buttons.
John:(To client) He means: "thank you."
An even better example was when Sherlock launches himself into investigating the kidnapping of two children with his classic enthusiasm for harrowing mysteries:
John: Having fun? Sherlock:(Grinning) Starting to. John: Maybe not do the smiling thing: kidnapped children? Sherlock:(Composing his face into an appropriately serious expression) Hm.
Every main character in It's Always Sunny in Philadelphia has taken this role towards another main character and vice versa, with resident full-time Cloudcuckoolander Charlie being the most common recipient.
In Supernatural, Meg becomes this to Castiel after he absorbs Sam's psychosis towards the end of season 7.
Bones herself is a brilliant scientist, but finds social situations difficult and confusing (although it should be noted that her social skills do get somewhat better over time), so Booth often ends up in the role of her guide to the world outside the lab. Especially in the early seasons, he often interrupted her to prevent her from saying something too scientific or brutally honest to a witness or a victim's loved one.
This role could also go to Angela or Cameron, who were both generally closer to earth than the other Jeffersonian staff.
Following in the great Watson tradition, Joan Watson on Elementary. It is, literally, her job to rein in Sherlock's self-destructive tendencies.
In the first episode of The X-Files, Agent Scully was assigned to the X-Files to keep an eye on Mulder, and she was supposed to regularly submit case reports from their investigations.
Dani Reese is this for her parter Charlie Crews in Life.
Warhammer 40000 has Ork Weirdboyz, the psychically receptive members of the Orkoid species whose barely-understood innate psychic powers make them, as the name suggests, a bit weird. By Orkish standards anyway, since they usually prefer to run away from the heavy fighting that makes their brain hurt rather than towards it as a sane ork would. As such they are usually accompanied at all times by two or more "minderz", unimaginative, no-nonsense ork thugs whose job it is to keep the weirdboy from doing anything too outrageous or running away when his mind blasts are needed in battle. This was the case on the tabletop up until the 3rd edition of the game, where the minders were represented with models and effectively fired the weirdboy like a living weapon. In the current rules the weirdboy has been safely escorted to the battlefield already, and the build-up of psychic energy has sent him crazy enough that he has given his minderz the slip and started to bounce around unpredictably on his own.
There is also the Necron commander Nemessor Zandrekh, and his long-suffering aide-de-camp and enforcer Vargard Obyron. Zandrekh is a consummate tactical genius who was instrumental in promoting his dynasty's fortunes during the ancient Necron civil wars. Unfortunately his cognitive processing circuits were damaged during his long hibernation into modern times, and while his genius is undimmed he can't tell the difference between the present and the past anymore, believing he's still fighting the civil wars against rival dynasties whatever new enemy he comes up against. Obyron, on the other hand, is perfectly aware of the situation, but as an indentured subordinate he was programmed for absolute loyalty to Zandrekh and so has to make the best of things and sort out any anomalies caused by Zandrekh's delusions. Usually this involves making sure that "honoured prisoners" kept alive by Zandrekh according to ancient rules of engagement are conveniently disposed of via "little accidents" or "while they were trying to escape".
The main characters in the Ace Attorney series tend to be this to their sidekicks (at the very least they occasionally manage to prevent them from doing something stupid).
A more serious version appears in The Suffering where there's an Escort Mission (optional, but you'll need to complete it to get the best ending) that involves guiding around a drugged up, traumatised teenager who's so out of it he thinks you're his father.
In Fallout 3 you essentially serve as this to Moira Brown when you're doing her (exceptionally long) quest chain to gather data for writing a survival guide. You can even talk her out of pursuing said dream (but only if you're feeling cruel).
At least some of the cast of BlazBlue try to keep Taokaka out of trouble when they can (particularly her progenitorJubei, his student Ragna and Tao's more level headed Cool Big Sis and mentor Torakaka, and occasionally, her 'very good friend' Litchi).
In Dragon Age II, Varric serves this role for his older brother Bartrand, who lacks social skills. Later on, he also serves this role for Merrill as she tries to adapt to life in the city.
Both examples get played more seriously after Bartrand goes insane from the Lyrium Idol. If spared, Varric is forced to commit his brother to an asylum for the rest of life. To a lesser degree, if Hawke does not romance her, Merrill becomes increasingly obsessed with restoring the Eluvian, to the point where Varric has food delivered to her house since she's stopped going out and forgets to eat.
In the beginning of Tales Of Symphonia, Genis serves as this for Lloyd. Raine also takes this roll with regard to Collette, to a degree.
Youmu Konpaku from Touhou often acts as this to her mistress Yuyuko Saigyouji. However, it's unknown if Yuyuko is really a Cloudcuckoolander or she just loves messing around. Whenever she's involved in something, Yuyuko is often shown to have figured out everything from the start, while Youmu acts as The Watson.
In Katawa Shoujo, Emi is the one who understands Rin's odd trains of thought better. Also, if you make Hisao pick Rin as his girl, he'll fit in here as well. Actually, Hisao is a deconstruction of the trope. In Rin's path, as poor Rin falls into depression and insecurity since her art is becoming popular but she can barely handle the huge attention and pressure on her, Hisao's own emotional stability will be put through the grinder as he attempts to help Rin but he can barely do so. If you pick the wrong options, this will lead to them breaking off their relationship and to the Bad Endings.
Louise of Miscellaneous Error spends most of her time trying to keep her brother, Jack, from killing himself or anybody else.
Lucas and Lilah in Ctrl+Alt+Del both fill this role for Ethan.
In Grey Is, White is very much this to Black, especially in the flashbacks to 2 years ago where we see a depressed anorexic Black who is only really happy when White is there to distract him. Even in the present time it is up to White to help keep Black from freaking out when he loses focus and can't remember things or when his boss starts nagging him.
Copernicus winds up being this to Fletcher on occasion in Antics. Sometimes.
Megatokyo: Piro is this to Largo, translating his l33t sp34k when necessary and trying to rein him in from trouble. Lately, however, Erika has been taking over the job—when she's not just running with the madness.
Church could be seen as this to Caboose in Red vs. Blue. He's entered Caboose's mind a few times, and also seems to be the only one who knows how to get results from Caboose, either through manipulation or genuinely getting through to him.
Agents Of Cracked has Dan hired to be this to Michael, an Idiot Savant who is completely insane and is implied to have caused the deaths of his last eight partners, but keeps his job because his articles (even if he writes them five minutes before publishing while asleep) are popular. Subverted in that Dan has no ability to keep Michael under control, as he just does what he wants anyway, and Dan undergoes considerable Sanity Slippage himself as a result.
Leela is this to Fry (being his boss) for the first few episodes of Futurama. After that, he adapts and stops being a Fish Out of Temporal Water, though she still takes on this role from time to time.
Leela: As I've said before, objects in the future are still just objects, not living things that seem like objects.
Fry: So my attempts to establish diplomatic relations with the Cactus People were doomed from the start.
The Planet Express crew frequently plays this role in regards to Professor Farnsworth. Left to his own devices, he probably would have destroyed the Earth, or worse.
Nani is this to Lilo in Lilo & Stitch. When Social Services threatens to separate them, she explains that she's the only one who can understand Lilo's actions.
James Hutton, the geologist responsible for putting forward an important aspect of plate tectonics, was known for having very strange speech patterns. When he died, a friend of his (who knew what he was on about) rephrased things for him.
It is not uncommon for exceptionally driven but socially lacking students in scientific fields to pair up with a mediocre but socially-apt student for part or all of their studies in order to make group assignments bearable.