Kid with the Leash

"Yami Yugi: Couldn't I just mind-crush him?

Yugi: You can't fix all your problems by mind-crushing people!

Yami Yugi: Oh, come on! Just one little mind-crush, it'll barely hurt him.

Yugi: No! Bad pharaoh! No mind-crush!"

- Yu-Gi-Oh the Abridged Series

The Kid With the Remote Control, but with a twist: the controlled partner or servant is pragmatic at best, and a raving loon at worst. The actual loyalty of the servant varies, but the typical example is essentially a portable version of Sealed Evil in A Can -- though a very loyal one is arguably even creepier. The servant openly admits his opinion that the best way to deal with obstacles and enemies is through complete annihilation. The kid (who is usually younger) is the moral compass who has to keep it under control (with a little help from the Restraining Bolt), and more importantly not fall victim to temptation.

Naturally this works both ways, where the monster learns empathy and grudgingly accepts his master might not be so bad, while the handler learns not all things are as black and white as they think.

This is one of two things that can result from trying to control Sealed Evil in A Can. For the other, less family-friendly outcome, see Evil Is Not a Toy. Compare Guardian Entity.

Anime & Manga

 * The title characters of Ushio and Tora. Ushio's the kid who keeps the demon Tora at heel with a magic spear, as the two begrudgingly cooperate in fighting demons.
 * Inuyasha, initially; in early episodes Kagome made Inu-Yasha behave himself with the help of a magic necklace that slammed him to the ground when she said the command word (osuwari, or "Sit"). She never actually stops doing this, but in later episodes it's usually provoked more by romantic-comedy wackiness than actually restraining him from violence.
 * Except in regards to his Super-Powered Evil Side.
 * After her father's death, Integra Hellsing likely spent the rest of her childhood holding the leash of the ravenous vampire Alucard -- which could well explain a lot about her personality. Something uncommon about this example is that Alucard's loyalty is real. He truly likes to serve Integra, he even respected her ancestor (Abraham van Helsing, the man who defeated and sealed him) having though of him as a Worthy Opponent.
 * In Mahou Sensei Negima!, Evangeline's first partner, the doll Chachazero, is a bloodthirsty thing that would rock Chucky's boxers. She often councils her mistress towards violence, murder, and mayhem. This is despite the fact that Evangeline herself is already a notoriously evil vampire sorceress with a huge bounty on her head...
 * Also inverted in Evageline's relationship with her other partner Chachamaru, a gentle-souled Friend to All Living Things of a Robot Girl.
 * Komachi and her "sidekick" Kikuchiyo in Samurai 7.
 * Shin'ichi Izumi from the manga Parasyte / Kiseijuu exists in an uneasy partnership with "Migi", the parasitic alien that took over his right hand while attempting to eat his head.
 * In a way, the title character of Naruto embodies this trope, as did Gaara before the events of Part 2. Naruto's "partner" is concerned mainly with protecting himself and therefore Naruto, and only aids him if he is in danger.
 * Besides keeping itself alive, the fox has an ulterior motive to letting Naruto draw on its power:.
 * In the recent chapters of Claymore, it's shown that Raki has essentially become the leash-holder for Priscilla, who's taken on a much smaller form since she apparently hasn't been eating people lately and has been helping Raki find Yoma. Priscilla, by the way, is more or less the strongest awakened being ever. Raki, however, admits that he may have to kill her at some point, and that she likely will eat him first if he tries.
 * In a mild version of this trope, Kaname Chidori from Full Metal Panic! inspires a great deal of loyalty and protectiveness from her bodyguard Sōsuke, who is both capable of and willing to unleash copious amounts of carnage to keep her safe (much to her chagrin). The pair's relationship is at one point described as that of "a rabid dog and its master".
 * Yugi from Yu-Gi-Oh! is an arguable example, once he figures out how to communicate with the 3000-year-old pharaoh possessing his necklace, and tells him that ideas of justice have changed somewhat in the last couple of millennia.
 * Subverted (and sometimes subverted again) in Chrono Crusade. Considering Rosette is in a contract with a demon, it seems like they'd have this sort of relationship, and Rosette's commander, Sister Kate, is openly suspicious of her partner. But Chrono himself is a kind-hearted person that, in the words of another character, "wishes not to harm anyone." However, he does have a Berserk Button that sets off his demonic instincts at times--meaning that occasionally Rosette does have to step in and order him to stop.
 * Nora: Magari Kazuma is a rare example of a Kid With the Leash who really isn't shy about yanking it; both he and the Dark Liege view his contract with Nora entirely through the lens of "obedience training" (not that you can really blame them).
 * Tsuna and Gokudera from Katekyo Hitman Reborn have a relationship rather like this. Gokudera seems rather eager to kill people he dislikes (which include pretty much everyone except Tsuna), with Tsuna constantly having to restrain him. His love for his boss is pretty much what keeps him from killing / beating up most people.
 * Ciel from Black Butler is a 12 year old rich kid in control of a demon who just happens to be working as a butler in his mansion. Sebastian, the demon, pretty much does whatever Ciel tells him to do. He won't do anything without Ciel ordering him to.
 * In Cyborg 009, we have a boy (0013) and a Mysterious Waif (Princess Ishuki) as the controllers of two enormous, murderous robots. Neither case goes well.
 * Naeka's hold over her 'servant' Kogarashi in Kamen no Maid Guy, who will use his wacky superpowers in increasingly outlandish and sociopathic ways to 'help' her. Said hold was tenuous at best even before the Restraining Bolt broke in the second episode and the only way to restrain him after that is with the good old Ultra-Violence.
 * In an omake story for Durarara, Tom's relationship with Shizuo is shown to actually be a subversion. Tom is actually insulted by suggestions that Shizuo is his to control ("The kid isn't a dog.") and, despite the fact that Shizuo was hired to be Tom's bodyguard, Tom actively avoids making Shizuo fight for him. In fact, several details (such as who pays for Shizuo's property damage) imply that Tom offered the job mostly for Shizuo's benefit.
 * There is however, a straight example with and Saika. Saika basically spends all of its time in 's head incessantly suggesting that she should let it "love" anyone and everyone, especially Shizuo.  is understandably a little distressed by this.
 * Yukki fills this role in Mirai Nikki. He is the only one that can stop Yuno whenever she tries to kill people. Considering they are in a life or death survival game, he has to let her loose more often than most.
 * While Alice likes to pretend otherwise, it ultimately IS Oz who holds the leash in Pandora Hearts. The terms of the contract between the teenage nobleman and the demonic, scythe-wielding 'Bloodstained Black Rabbit' are uncertain at best, but Oz's superb willpower means that he can effectively shut down Alice if she gets out of hand.
 * Bastard!'s Dark Schneider was all about this. A virgin maiden's kiss and a spell released him from his childish body and transformed him onto the cruel, evil and horny black mage.
 * The Loveless manga seems to be headed this way, with Ritsuka holding Soubi's leash when he wants to "deal with" Ritsuka's mother in violent (and permanent) fashion. Lately, he's also started down the "teaching morality" track.
 * Virgin Ripper: Nagi is a kitten who becomes a cat-boy shinigami (think Schrodinger with Captain Kuro's sword gloves). After being traumatized he thinks the title "Ripper" is his mama and will do anything to protect her, including "making squishy" anyone who threatens her, even her friends. She will no doubt try to correct this but trauma or not Nagi is still a cat.
 * In Kamisama Kiss an ordinary teenage girl, Nanami Momozono, is made the new Land God of the Mikage shrine and ends up with Tomoe, a powerful and ruthless demon, as a familiar. He is none too pleased about having to serve Nanami  but thanks to the familiar contract is forced to obey any order she gives him.
 * In Kamisama Kiss an ordinary teenage girl, Nanami Momozono, is made the new Land God of the Mikage shrine and ends up with Tomoe, a powerful and ruthless demon, as a familiar. He is none too pleased about having to serve Nanami  but thanks to the familiar contract is forced to obey any order she gives him.

Comics

 * Jaime Reyes with the scarab. Much of the dialogue between the two consist of Jaime rejecting its suggestions to kill somebody. According to Metron, it shouldn't even have a "non-lethal setting."
 * The DC-Verse being pegged way on the sunny end of the Sliding Scale of Idealism vs. Cynicism, though, the scarab eventually comes around completely to its partner's way of thinking.
 * In the 2011 reboot It Got Worse. The scarab is an Ax Crazy killing machine that barely responds at all to Jaime's wishes. Jaime had to flee his hometown to prevent the Scarab from killing everyone around him. This is still a better deal for Jaime, since the Scarab normally should have taken full control of him.

Films -- Live Action

 * In Terminator 2: Judgement Day, John Connor discovers early on in the film that he has complete verbal control over the Terminator cyborg played by Schwarzenegger. Of course, he also learns he has to word his instructions carefully -- an instruction to not kill anyone leads to a guard getting shot in the leg, with the explanation, "He'll live."
 * Leads to possibly the best line in the film. "Jeez, you were gonna kill that guy!". "Off co-uss. Am a Terminader."
 * 'The premise of Danny the Dog (known as Unleashed in some countries) is a variation in which a gangster has raised a man as a dog - a dog with deadly martial arts skills - who, when he has his collar removed, serves his master's whims rather than his own, mainly debt collection and pit fighting. Guess what happens...

Literature

 * Good Omens: To signify The End of the World As We Know It, the Antichrist is sent a fearsome and terrifying hell hound that is his to command. However, as the Antichrist has grown up as an ordinary boy who is completely unaware of his destiny, upon its arrival he unwittingly commands it to become an ordinary pet dog -- and as the novel progresses, the hound becomes progressively less interested in tearing the throats out of the innocent and more interested in chasing cats.
 * Deconstructed/subverted in The Bartimaeus Trilogy: Nathaniel (an apprentice magician) firmly believes that demons are Always Chaotic Evil, and that elaborate incantations and careful wording are necessary to keep enslaved summons in check. While this is not entirely unjustified (Bartimaeus is very open about his willingness to free himself by killing Nathaniel if he had the chance), Bartimaeus -- the demon -- is often more moral than Nathaniel. He complains about being given less-than-ethical tasks, and there are hints throughout the series that both the djinni and the boy would be better off if Nathaniel relaxed the restraints and simply trusted him.
 * The rule is kept, however, with Bartimeaus' favorite master,
 * Mogget in the Old Kingdom trilogy by Garth Nix. He's an incredibly powerful and very, very angry Free Magic creature, but a powerful Charter Magic spell in his collar locks him into serving the Abhorsens and cuts off a lot of his power. If the Abhorsen takes off his collar, he returns to his original form and helps them for a little bit. Unfortunately, he then starts on a Roaring Rampage of Revenge against the people who've been controlling him for centuries.
 * There's an odd example in the Discworld series with Death and his servant Albert, with Death being the "kid" and Albert the one on the leash. In life, Albert was a malevolent wizard and, when he knew he was going to die, performed - in reverse - a ritual that was supposed to summon Death, on the logic that it would send Death away from him. Instead, it sent him to Death. Albert has "lived" for centuries in Death's Domain and can now only spend a limited time on earth before his remaining minutes of life are used up. While Albert is not a physical threat to Death, he is much more cynical than his master, and in several books evidences a willingness to betray his master and regain his status in life.
 * It helps that Albert is heavily implied to be vastly more powerful than his wizened, chain-smoking form would lead you to believe. Albert and Death are fond of one another in an odd way though.
 * Possibly the most extreme leash is from Terry Pratchett's Small Gods where Brutha -- the humble servant -- holds Om's -- the omnipotent deity -- leash as the last person who believes in him. Since a god's power and very existence is based on belief, Om has to follow Brutha and keep him interested in worshipping him.
 * And of course, Rincewind theoretically has this relationship with The Luggage, occasionally trying to stop it from completely slaughtering everything in the vicinity.
 * Heroine of several Forgotten Realms short stories (Thieves' Reward, Thieves' Honor, Thieves' Justice) by Mary H. Herbert, thief Teza managed to swindle Anti-Villain out of magically bind an aughisky - a very rare sentient humanoid-eating horse. She both rode him and got rid of many enemies by her monster's teeth. Teza loved even normal horses and cared very well for the most cool and beautiful mount she ever saw. That paid off when control was broken: instead of simply devouring her, the aughisky
 * A mild version in the Honor Harrington series. Sphinxian Treecats believe that there are only two kinds of enemies: Those who are dead, and those who are not yet dealt with. This is due to a combination of the unforgiving deadliness of many predators on Sphinx (including the Treecats themselves), and the fact that the Treecat trait of Telepathy means that there's no point to being subversive or subtle in Treecat society: They all know what you're thinking anyways. It's a mild example because, while that's a rule in Treecat society, they understand that such a mindset is not shared by most Humans and behave themselves while amongst them.
 * Lest everyone forget...look no further than Journey to The West - this is very essence of the dynamic between Xuanzang and Sun Wukong.

Live Action Television

 * Mike holds the leash of Vyvyan on The Young Ones.

Puppet Shows

 * On The Muppet Show and all movies featuring the Muppets, Floyd seems to be the only one who can keep Animal under any sort of control.

Tabletop Games

 * An example of the rarer, more loyal variant: In the Dungeons and Dragons campaign setting Ravenloft, the class-based critters of wizards (familiars) and paladins (holy steeds) are transformed into entities known as "Dread Companions". These perverted versions of the ordinary companions are totally evil, but remain slavishly devoted to their master, to the point of acting on his or her subconscious desires.
 * Zealotry abound in Tormenta. Servants of the goddess of Life revere fertility, healing, life and the product of those: Kids. The city of Smokestone is home to the Children, a group of clerics of Lena that pledged their loyalty to a group of kids that they raise. Even though they learn to never harm other people (it's part of Lena's restrictions), having kids leading over a bunch of adults with the power to channel the wrath of a god is an excellent way to show how evil those little bastards can get.
 * Monsters and Other Childish Things is essentially Kid With the Leash : The RPG

Video Games

 * Yuna from Final Fantasy X A 17 year old girl (so yes, she's still a 'kid' ) who can summon a large number of beasts to fight for her.
 * Though this can go for many of our younger Final Fantasy main characters (remember the oldest main protagonist is 21 in the entire 1-10 set so there are bound to be kids summoning monsters of epic proportions)
 * Eiko from Final Fantasy IX would be a prime example.
 * In Star Wars: Knights of the Old Republic, the assassin droid HK-47 enthusiastically offers to kill almost every character you meet. (Whether or not you allow him to do so is up to you.)
 * In Summon Night: Swordcraft Story 2, the player may choose the half-angel, half-devil Dinah as their Guardian Beast. Her devil half claims to be heartless and evil, and that she's forced by circumstance to work for the main character. Her catchphrase is "I guess I don't have a choice", whenever Edge/Air announces his/her plans to do anything. Her failure to be completely evil is just that blasted angel interfering plus enlightened self-interest, honest! No, really!
 * Van Vun Chan and his minion Archibald Grimms in Super Robot Wars: Original Generation 2, who keeps Archibald in line with careful instructions, insanity notwithstanding... mostly to keep him from slaughtering civilians. For a villain, Van isn't a bad guy.
 * Felt holds the leash of the Azure Azoth in Atelier Iris 2: The Azoth of Destiny. The all-powerful sword (capable of destroying continents) insists on killing to get rid of obstacles and complains about Felt's moral choices.
 * The premise of the game Okage: Shadow King is somewhat of an inversion of this, as the kid with the leash is actually subservient to the Omnicidal Mani... er... evil demon king. At least, in theory...
 * Street Fighter III has Hugo, a brutal, beastly mountain of a man... who is kept in check by his manager, Poison.
 * The protagonist of Soul Nomad and The World Eaters, who keeps Omnicidal Heroic Sociopath Gig on a very short leash by having imprisoned Gig's soul inside his/her own body and extracting minuscule amounts of godly power from Gig as a form of lease for having him stay there. Gig, on his side, finds the protagonist repellently noble and constantly tries to goad the protagonist into doing acts of evil or tempting him into accepting more of his powers, which will grant Gig more control over the protagonist's body.
 * An interesting subversion can happen during a New Game+, Who of course finds the whole thing hilarious and starts handing out power like it was Christmas time. Right up until he realizes that
 * Several of the demons/personae in the various Shin Megami Tensei games border on this. You know, because so many of them are Olympus Mons.
 * Subverted in several ways with Touhou Project and Remilia/Flandre. Fits because Flandre is Ax Crazy insane and only Remilia (and to lesser extent Sakuya, her maid) keeps Flandre under control. Subverted because Flandre is actually younger than Remilia (not by much though), because they're both about 500 years old vampires, and because they're actually sisters.
 * in Rule of Rose controls

Web Comics

 * In Gunnerkrigg Court, the demon Reynardine possesses one of the protagonist's old toys. Unfortunately for Rey, because she owns his current host, she also owns him; he more or less has to do as she says.
 * Later revelations indicate that this wasn't necessarily entirely unintentional, though whether the ownership deal was a part of the plan is unclear. In this universe it seems that "demon" is a pejorative term more an anything in this universe, in any case.
 * The Order of the Stick, where Roy (Lawful Good fighter and party leader) is one of the few things keeping Belkar (Chaotic Evil halfling ranger and barbarian) in check. Occasionally with a magical Restraining Bolt, but not as the main tool.
 * The cast of Sluggy Freelance try to do this with Bun-Bun. They don't have much in the way of actual control over him, but they've gotten rather good at arranging situations so it's in Bun-Bun's best interest to help them. Or at least in his best interest not to skin them alive.
 * Goblins has an inversion in Kin, a kind and heroic yuan-ti (snake-person), kept on a literal magical leash by the significantly less benevolent Captain Goblinslayer.
 * The undead warlock Richard from Looking for Group is an Omnicidal Maniac held back (sometimes) by group leader Cale. Though as Richard is, by far, the strongest member of the group, Cale has had to be a bit more tolerant than Roy.
 * The Heterodyne family of Girl Genius serves as a family of psychopathic mad scientists with the leash to Castle Heterodyne. Agatha is the first one in a long time with any empathy, kindness, or respect for other humans. However, Agatha has to watch how she orders the Castle. It tends to interpret her orders... creatively.
 * She's not the first--her father and uncle were the "Heterodyne Boys", who were heroic adventurer sparks who tried to help other people as well. This trope applies in several more cases, too--the Heterodynes had lots of servants to the line, including the Castle itself, the Jagers, and the people of Mechanicsburg. Agatha, through her mother's Compelling Voice, also has some degree of control over several of the geisterdamen, the slaver wasps and creatures, and anyone infected with the new slaver wasps.
 * In Manly Guys Doing Manly Things Jared the ex-Pokémon trainer has a Gyarados which he named Mr. Fish as his partner. He was kicked out of the Pokémon League because he wasn't tight enough with the leash and allowed Mr. Fish to eat his competitors. Aside from this Mr. Fish is completely loyal to Jared.

Western Animation

 * Lydia Deetz from the cartoon version of Beetlejuice is the only character who can keep the eponymous Anti-Hero under control. Of course, it also helps that saying "Beetlejuice" three times imprisons him as well as releases him, in case he gets too out-of-control.
 * In The Grim Adventures of Billy and Mandy, the Grim Reaper is forced to become the best friends of Mandy (a sociopathic Creepy Child) and Billy (who's dumber than pond scum).
 * Mina and The Count. Vampire mellows out for a little girl.
 * Jade once got control of the Shadow Khan. It was....interesting, to say the least.