The Big Bad has an assistant or sidekick to whom they spend a lot of time bragging to about just how clever they are. Near the end, their assistant double crosses them spectacularly while their back is turned. Essentially, this is Deceptive Disciple, except that the Bastard Understudy is apprenticed to an Evil Mentor.
In many cases the Bastard Understudy appears to have been groomed as a successor of sorts. While the Big Bad hates the idea of defeat, they know they are not going to live forever, and the Bastard Understudy offers a continuation of their legacy. A sublime game of Xanatos Speed Chess keeps the Bastard Understudy just out of reach of the power... until the last play.
The Starscream is a visible rival who lacks the Bastard Understudy's loyalty and patience. The Dog Bites Back is when the betrayal is not premeditated. May be a form of Thanatos Gambit. See Magnificent Bastard, Manipulative Bastard, Villain Takes an Interest, and The Chessmaster for characters who are likely to have one of these around. May overlap with Dragon with an Agenda. Definitely overlaps with Rule of Two.
- Code Geass: This is the modus operandi of the Big Bad Social Darwinist Emperor. By raising a family of Bastard Understudies and then encouraging them to plot and scheme against each other - and himself - over the throne, the Emperor hopes to produce a strong leader for Britannia. If Lelouch is anything to go by, his methods are quite effective. In reality, this is all a feint to distract them from his true motive: activating the Sword of Akasha and destroying God.
- And the trope itself plays out with Schneizel and Charles. Schneizel prepares to assume command of Britannia and leaves Charles on his own. However, Lelouch killing Charles forces Schneizel to go into hiding.
- "Fucking Ribbons" Almark in Mobile Suit Gundam 00. He appears to be a harmless toady of the apparent Big Bad Alejandro Corner, only to reveal himself as the key villain while Celestial Being kills Corner at the end of Season 1.
Alejandro Corner: RIBBONS!
- In Naruto Kabuto and Sasuke represent the two different types of this: the latter learns all he can from Orochimaru and then "kills" him, while the former, after witnessing Orochimaru's death, has become obsessed with carrying on and perfecting his legacy. To be fair to Sasuke, in this particular case he acted out of principle- he might have planned on dumping Oro from early on, but he only killed him because he saw Orochimaru as an evil, sadistic psychopath who had abandoned whatever higher purposes he once pursued, every bit as bad as the mass murdering brother he was training to kill. Which is exactly right, despite the irony that Sasuke himself would later go in the same direction.
- Katsumata in 20th Century Boys, who takes advantage of Fukubei/Friend's Thanatos Gambit plan to kill him for real and take his place on the viewing platform.
- Mar Omega: Atoms betrays Unwetter by erasing him from the Anti-Bobo, and then declares that there is no god so he has to become one.
- Inverted in The Metabarons, where the heroes have this as a tradition.
- In The DCU, during Rogues Revenge, Zoom freed Inertia to train him into torturing superheroes on the grounds that it would make them better heroes. At the end of the series, Inertia murders the Weather Wizard's child and calls himself Kid Zoom. Zoom objects because that would not improve them. Inertia says he just wants to hurt them and reverts Zoom back to the cripple without superspeed. (The Rogues then kill Inertia.)
- Inverted in Necrophim - everybody thinks Uriel is trying to usurp the throne of Hell, but he just wants to loyally serve Lucifer.
- Doctor Doom was supposedly one of these in the Mark Millar run on Fantastic Four.
- Used in High School Musical 3. Sharpay gets an assistant who becomes her understudy in the play. Near the end she tries to take advantage of one of Sharpay's failed plans:
Sharpay Evans: But... you were so loyal. And sweet.Tiara Gold: That's called acting. You should try it sometime.
- From The Chronicles of Riddick, Vaako is the Lord Marshal's second-in-command, but thanks in part to his wife's promptings, takes his opportunity to betray him in his final fight with Riddick, for the good of the Necromonger faith.
- Repo! The Genetic Opera subverts this with the Largo siblings—Rotti would like them to be ruthless, manipulative, and cunning enough to take over his empire, but they just don't cut it. Later Amber, against all expectations, convinces her brothers to back her as she takes control of Gene Co, but only because the chosen heir, Shilo, turned it down. Shilo would have had to kill her father to inherit the position, but she refused to.
- The Mechanic (1972). Charles Bronson plays the assassin for the mob, who grooms Jan-Michael Vincent's character (Steve McKenna, son of a dead mob boss) as his backup. Eventually, Steve decides he'd rather take over the main job. It doesn't end well.
- Jigsaw from the Saw movies has passed on the secrets of his lethal Games to at least two such Understudies, Amanda and Detective Hoffman. Subverted in that neither of Jigsaw's apprentices actually share his make-your-choice philosophy: The first can't stand to leave any survivors to cope with their trauma after her Games, while the second just likes torturing people. And then, in the last twist of the series, Jigsaw is shown to have had a third apprentice, Dr. Gordon, who was loyal to his philosophy and is carrying it out "properly".
- In Hellraiser: Bloodline, Jacques and his mentor the Duc de l'Isle are satanists who dabble in the dark arts by summoning demons. They summon one in the form of a Demon Princess, but Jacques quickly murders the Duc to be with her.
- In Dune, Feyd-Rautha Harkonnen serves as the Bastard Understudy to Baron Harkonnen. Feyd-Rautha actually launches at least one assassination-attempt against his uncle, but fails primarily due to bad luck. H never really gets around to usurping the throne - the Baron dies by the Gom Jabbar before he gets the chance. And Feyd dies in a duel against Paul soon after anyway. Feyd is punished by the Baron as a result of the attempt on his life. Not for trying to kill him, but for FAILING.
- In Stardust, the seven princes of Stormhold are always killing each other to strengthen their claim on the crown. Septimus is clearly the champion at this, and the reigning Magnificent Bastard of the book/film. So it should come as no surprise that Tertius, his much older brother, makes an attempt on his life. And fails, miserably. While Primus, the oldest and wisest, spends most of his time avoiding Septimus. This apparently the expected method of gaining the throne - the old king is quite disappointed he still has more than one surviving son on his death.
- L.A. Confidential: Bud White becomes an enforcer for Magnificent Bastard Dudley Smith, learns a few tricks on the way then turns on his mentor.
- Lensman. Among Boskone (and their controllers, e.g. the Eddorians) it is regarded as quite acceptable, even praiseworthy, for an underling to scheme to supplant their superior — the idea being that if he's successful the superior is no longer fit (e.g. not cunning and ruthless enough) to hold their position anyway.
- In C. S. Goto's Warhammer 40,000 Blood Ravens trilogy Dawn of War, Ahriman reflects on Magnus outdid the "False Emperor" and how he outdid Magnus — and how he keeps his own Prodigal Sons down, so no one would supplant him. (For instance, there is no Book of Ahriman, as there as a Book of Magnus, because he stole it.)
- In The Voyage of the Jerle Shannara The Ilse Witch is Bastard Understudy to her former Evil Mentor, and current partner in crime The Morgawr. They're both very aware of it, and it defines their interactions with one another, the Witch always seeking to gain more authority in their relationship, while The Morgawr asserts every last ounce of control that he can over her due to his senior position. Interestingly, she never manages to replace him instead pulling a Heel–Face Turn. Then again, she was never even remotely as evil as him.
- Duke Vessegno to Astfgl, the Satan-figure in Eric. When Rincewind sees them together his first thought, referencing Astfgl's similarity to a Panto Demon King, is "Look out, he's behind you."
- This is the whole point of the Sith Rule of Two in the Star Wars Expanded Universe. To maintain the Sith organization, a Sith Lord intentionally takes on a Bastard Understudy apprentice in order to supplant and overthrow him when he becomes too old and/or weak. This is to prevent the Sith from destroying themselves, as a group of many Sith Lords would always succumb to infighting with each member vying to rule all.
- A Song of Ice and Fire gives us an example of how this kind of relationship can develop. Sansa Stark starts out a lost Fish out of Water in a Deadly Decadent Court, and pays for it in spades. However, she does end up being taken under the wing of somebody willing to train her up, even though she is still very much being used and nothing about the relationship is particularly healthy. There are a number of ways it could end up, but her killing her mentor by direct or indirect means is possibly one of them, as she has enough motive to go that route.
- A rather literal one happens when Little Walder Frey becomes The Squire to Ramsey Bolton. He took to the lessons so well, he didn't manage to get to the "kill the mentor" stage; as it turns out, aiming for monsterdom as a career when you have little native cunning means somebody else with a bit more insight as to where this is going will have enough motive and ability to murder you, first. Most likely out of pre-emptive self-defence.
- Game of Thrones: By the end of Season 4, Sansa becomes this to Littlefinger, impressing him by willingly protecting him from the nobles of the Vale with manipulation techniques she's learned from his various monologues. She has also thrown in with his plans while gaining some leverage against unwanted advances. Needless to say, Petyr is impressed by this. By the end of Season 7, she puts his lessons to good use. On Littlefinger.
- Believe it or not, Big Bad Astronema from Power Rangers in Space fits this. The Psycho Rangers were designed more to drain energy from Dark Specter than to destroy the rangers themselves, thus letting Astronema take over as Queen of Evil. Several scenes from this mini-arc consist of Dark Specter imploring loyal Astronema to find the traitor draining his power, never realizing that she's looking him right in the eyes and lying to his face.... And all of this was after he went to the trouble of luring her back to his headquarters and using cybernetic implants to brainwash away her Heel–Face Turn!
- Apparently taking away her ability to feel positive emotions didn't make her more reliable. Go figure.
- At first, almost completely averted, then played straight with a twist in American Gothic (1995): Sergeant Ben Healy is certainly not being groomed to be Sheriff Buck's replacement—instead he lives constantly on the edge as his conscience (in the form of Merlyn) is at war with his cowardice and his loyalty to Buck, whose only plan consists of constantly balancing the two sides of Ben so that the cop won't reveal what he knows about Merlyn's death. Meanwhile, Buck actually is grooming a successor...his son, Caleb, who does indeed turn on him in the end.
- In the Doctor Who story, The Caves of Androzani, the Corrupt Corporate Executive's secretary deposes her boss, taking over his businesses.
- And exactly the same thing happens in "Dalek".
- Richard Smith-Jones to Holly Day in Slings & Arrows. Although he didn't so much usurp her as tell her to piss off, after his Heel–Face Turn. It didn't stick.
- Actor Masato Uchiyama has played two such characters in the Kamen Rider franchise: Yoshio Kobayashi/the Rabbit Orphnoch in Faiz and Shun Kageyama/Kamen Rider Punch Hopper in Kabuto.
- Jamie from The Thick of It acts as this to Malcolm Tucker. He’s Malcolm’s unofficial second-in-command and his Violent Glaswegian tendencies come in useful whenever Malcolm needs help bullying government ministers, but in the Christmas specials Jamie makes his own play for power when he goes behind Malcolm’s back to get his own candidate in the leadership challenge put into power.
"Right, I'm off to deal with the fate of the planet. Be gentle with them."
"Oh, you know me, Malc, Kid gloves — but made from real kids."
- However, this just reveals that Malcolm has chosen his Bastard Understudy carefully; while Jamie is useful to Malcolm and certainly is not unintelligent or incompetent, compared to Malcolm Jamie is just a bit of a shouty, violent bully whose Hair-Trigger Temper and resulting lack of charm means he lacks the ability to truly be a threat. Accordingly, Malcolm is largely unconcerned by Jamie’s manoeuvre because he knows it will ultimately fail, as it does.
- In season 2 of Buffy the Vampire Slayer, Spike is stuck pretending to be a loyal mercenary to the prophesised leader of vampiredom until, after all of one episode he gets bored and burns the kid into ash.
- Then has to spend the second half of the season playing the role again to Angelus (this time while waiting to heal and then pretending to still be crippled until he found his moment to strike).
- Smallville: In Season 10's "Luthor" Clark visits an Alternate Universe in which he, Tess, and Lex all played this role to Lionel Luthor. Lionel plays the three of them against each other, hoping that the constant competition, and his belittlement of them will eventually drive one of them to kill him, ensuring that he and LuthorCorp (which is very close to being The Empire in this world) will have a worthy heir. None of them can quite pull it off though. Following his escape into Earth-1, the search for a new Understudy becomes a defining part of Earth-2 Lionel's character, and he makes repeated attempts to draft Lex's clone, Alexander, into fulfilling this role. That having failed, he may be cutting a deal with Darkseid in order to get the original Lex back.
- The Shadow Line is full of them. Ratallack to Bob Harris, Jay Wratten to his uncle Harvey (and later Joseph Bede) and Patterson to Commander Khokar — all of whom eventually supplant their superiors and join Gatehouse in his new Counterpoint. Gatehouse himself is implied to have been working to undermine the Counterpoint leaders even before they tried to kill him.
- In C-drama The Holy Pearl, a loose adaptation of InuYasha, Hu Ji (Kagura-Expy) is this to Naraku/Ghost King. She resents being subordinate to him and spends a considerable part of the series trying to arrange his demise. And eventually almost succeeds.
- This is D'Angelo's role in the Barksdale Organization in Season 1 of The Wire. He's being groomed and taught to someday be the man of the family and inherit the business from his drug kingpin uncle, Avon. Secretly, however, D'Angelo has grown extremely jaded about both the drug trade and his family planning out his whole life for him, and is practically dying to go all Defector from Decadence.
- On Justified Bo Crowder was grooming his eldest son Bowman to be his right hand man and heir but while Bo was in prison, Bowman's wife had enough of the beatings he gave her and shot him dead. Bo then tries to recruit his second son Boyd to be The Dragon of his criminal empire but Boyd is going through a Heel–Faith Turn and rejects Bo. Bo finally turns to his nephew Johny who accepts the position but is secretly quite resentful of the 'third choice' part. Soon enough Johny is conspiring with Boyd to take Bo down but Bo is onto him and Johny ends up crippled for life. When Bo dies and Boyd takes over Bo's operations, Johnny becomes Boyd's second in command and this time hides his resentment better. However, when Johnny does make another grab for power, he is outmaneuvered by Boyd and has to go into hiding.
- A flashback reveals that Once Upon A Time In Wonderland's Big Bad Jafar 's Magic Staff is actually his old mentor who he forcibly transformed to retain access to her power.
- Megara in NBC's Hercules serves as Alcmene's disciple and the two work together to ruin the life of Hercules. To her credit, she admires Alcmene and is loyal to her until she witnesses her husband cheating on her with Alcmene's son Iphicles, realizing they were both trying to replace her. Megara arranges for Iphicles to be sacrificed in front of his mother no less and lets her know that she is responsible for Megara's treacherous ways. This ironically ends up triggering Alcmene's Heel–Face Turn.
- In Jersey All Pro Wrestling, Mace Mendoza and Buff E started going after one of their trainers, Laithon, in 2001 after they brought Chris Cabana into the Christopher Street Connection. It was less turned on and more "turned on to" in this case.
- Tasha Simone complained that this was a common problem in professional wrestling. She then offered to take Mschif under her wing, to bring out her full potential. MsChif came to PGWA to avenge her own student by kicking Simone's ass. Not hard to see how Tasha ended up with so many bastard understudies.
- Chris Jericho spent all but his first few sentences of the first WWE NXT contest talking about how great his 'rookie' Wade Barrett was. When The Nexus was started by Barrett, who won by virtue of Jericho refusing to support anyone but Barrett, Jericho decided to cash in on his loyalty and join them, only to get beaten down and thrown aside.
- KENTA was this to Mohammad Yone. He showed his loyalty to Yone by taking out his own Tag Team partner, Go Shiozaki, after which Yone granted KENTA entry into his Power Stable, Disobey. KENTA would then gather Yoshinobu Kanemaru and Genba Hirayanagi to oust Yone from the group, which he then renamed No Mercy. History repeated when Maybach Taniguchi showed his loyalty to KENTA by taking out his own tag team partner, the very same Go Shiozaki. Taniguchi would go so far as to help KENTA win the GHC Heavyweight Tag Team titles off of TNA wrestlers Magnus and Samoa Joe, but even while this was going on he introduced a new partner for himself in Maybach Taniguchi Jr. When the belts were lost, the Taniguchis turned on KENTA and revealed they were moles within Pro Wrestling NOAH, who had infiltrated its most powerful stable on the behalf of CHAOS. Maybach then stole KENTA's GHC Heavyweight (singles) title belt.
- From PGWA again came the story of Sin-D and Nemesis, the latter even stating Sin-D's biggest mistake was giving her students so many secrets so freely after using them to takeout her teacher.
- The Bullet Club, NJPW's Foreign Wrestling Heel stable, spent its first over 2½ years as a solid unit of True Companions, whether led by Prince Devitt or by Karl Anderson and AJ Styles. During this time, they had brought in Kenny Omega as a Psycho for Hire Cobra Wesker to take care of business in the junior heavyweight division as Devitt used to before going to WWE. Then on New Year's Dash 2016, the night after Wrestle Kingdom 10, Kenny followed the example of the original Wesker before him, betraying AJ Styles and convincing the group to follow his leadership to send Styles on his way to join Devitt. Rather than fight for the leadership nod, Anderson left for the same pastures along with Luke "Doc" Gallows less than two months later, solidifying Omega's place along with The Young Bucks as The Elite.
- In The Lion in Winter, Henry II deliberately encourages conflict amongst his sons to toughen them up for their role as leaders. He specifically grooms his inept youngest son, John, to take over as his successor (and has a Heroic B.S.O.D. when he discovers the boy scheming to usurp him with one of his other sons and the King of France.)
- X-Men Legends II: Rise of the Apocalypse casts Mr. Sinister in this role to that game's Big Bad, Apocalypse. With predictable results.
- Samir Duran is Kerrigan's understudy in StarCraft I. Not quite as magnificent as Kerrigan, but close. Or so it seems...
- In Starcraft II Heart Of The Swarm, Kerrigan cultivates the Broodmother Zagara as a potential replacement for leader of the Swarm. Zagara for her part is honest about her intentions to take over if the situation rises, but she also acknowledges that Kerrigan is the better leader and is content to learn as much as she can from her.
- Advance Wars 2: Black Hole Rising Hawke ends up killing Sturm at the end of Campaign.
- Oh dear. Vanitas to Master Xehanort in Kingdom Hearts: Birth by Sleep.
- Ansem's betrayal by Xehanort and the original persons of Xigbar, Xaldin, Vexen, Lexaeus, and Zexion
- Doubly so in the case of Braig/Xigbar. Out of all the Apprentices, he and Xehanort were the only ones who were bad people before they succumbed to darkness.
- Also, Riku to Maleficent to a certain degree. But ultimately subverted in that Riku himself never betrays her; instead, the Heartless of the aforementioned Xehanort possesses him and does the job instead because Maleficent Has Outlived Her Usefulness.
- Ansem's betrayal by Xehanort and the original persons of Xigbar, Xaldin, Vexen, Lexaeus, and Zexion
- Fawful shows shades of this in his final scenes in Mario & Luigi: Superstar Saga. Sure enough, by the time of Bowser's Inside Story, he's a full-blown Dragon Ascendant.
- The Final Fantasy series is fond of this trope. Kefka and Kuja both betrayed the evil masters who originally gave them their powers to become the game's true Big Bad.
- In Star Wars: The Old Republic, the Sith Warrior and Sith Inquisitor can both be played like this, biding their time and preparing themselves for when their masters inevitably decide to screw them over.
- Zig-zagged with the Sith Inquisitor's apprentice Xalek. Much of his idle dialog is him talking about how he's biding his time and waiting for you to show weakness. In-practice, he's rather obedient and respectful. In the Knights of the Fallen Empire expansion, he'll even return to serve the Inquisitor without question (whereas with other classes he challenges them to a fight) despite the fact that he is now a Sith Lord.
- Happens a few times in Survivor: Fan Characters: in Season 3, Baxter took Hope under his wing and taught her the joy of backstabbing her closest friends; in Season 5, Jessica taught Marius the ropes of Survivor, and after the merge, he organised her blindside, and eventually won the game; also happened in Season 6 with Vinnie and Sin, but this didn't go as far as the previous examples.
- In Girl Genius, Tarvek temporarily acts as a Bastard Understudy to Lucrezia after she takes over Agatha's body. He helps her with her projects, mixes her stimulants so she can get more work done in the time they have available, and puts up with (and occasionally reciprocates) her incessant flirting. He even agrees to sabotage Agatha's project that she worked on when she managed to temporarily regain control of her body and implants another of Lucrezia's personalities into the mechanical body of his dead sister. The entire thing is a trick to keep himself and Agatha alive after his plan to help her escape failed, and in helping Lucrezia with her work he discovered enough to be able to reverse the effects of her slaver wasps, create a potion to make people Immune to Mind Control, and work out how to get Lucrezia out of Agatha's head.
- In The Gamer's Alliance, Jemuel is groomed by Dante Albrigant to become a powerful sorcerer and help him usurp power in the clergy, but he ends up backstabbing Dante in the darkest hour.
- The PFY from the Bastard Operator from Hell saga - though the titular Bastard has raised him to do this, and always gets his revenge for each and every betrayal. Ah, kids these days...
- Starscream in Transformers wishes he could get away with this and tries many times to no avail, as he is not the Bastard Understudy but the Trope Namer for The Starscream. He almost gets away with becoming this trope in Transformers Prime when Megatron seemingly died.. unfortunately for Starscream, he turned out to merely be in a coma.
- In the Beast Wars episode "Possession", Blackarachnia betrays Megatron for Starscream (yeah, that Starscream), convinces him to take her under his wing, and then double-crosses him for Megatron at the end of the episode. Starscream can't catch a break.
- She was also a Bastard Understudy to Tarantulas.
- The Galaxy Force AKA Cybertron version of Starscream IS this however. And he succeeded in double-crossing Megatron until the writers brought him back.
- She was also a Bastard Understudy to Tarantulas.
- Snively in Sonic Sat AM. Inverted somewhat since while Robotnik is perfectly convinced he is under his thumb, he does not view Snively with much high regard outside a toady and a punching bag. Snively merely picked an opportune time Robotnik had (supposedly) desposed of himself (with Word of God stating his rule would not have lasted long before the new Big Bad entered the fray). This is played with in the Archie comics where Snively has made numerous short lived attempts to overthrow Robotnik, to the point the latter just considers it a fun little game of "roulette".
- Gargoyles: Thailog was this to Xanatos, but by the time he makes his first onscreen appearance, he's already decided that he's learned all he can and is ready to strike out on his own as a villain in his own right. He does nearly kill Xanatos, Goliath, Elisa, and Sevarius as a parting gift.
- Princess Azula from Avatar: The Last Airbender seems to have been this to her father, but ultimately with a couple of twists- first, that she's already smarter than he is (or at least more willing to use smarts instead of force) by her first appearance, and second in that the finale proves her to be genuinely loyal to him. Thus many Fan Theories of her being The Starscream/ Dragon Ascendant were Jossed.
- Slade of Teen Titans actually wants one of these (yes, including the betrayal part, as his dialogue with Robin makes clear when he complements him on threatening him- it'd keep him sharp if nothing else). So far, however, he's had phenomenally bad luck in keeping one, and lampshades this at one point.
Blood: Was anyone at my school actually there to learn?
- Brother Blood, who ran a school for apprentice supervillains, lampshades his own failure with this trope, when both his newest student and his star-pupil turn out to be undercover good guys rather than neophyte Bastard Understudies:
- On Jimmy Two-Shoes, every member of the Heinous family is this, being groomed to overthrow and freeze their fathers. In one episode, Beezy temporarly becomes this thanks to Screw Learning, I Have Phlebotinum!.
- In Transformers Prime, the newest Starscream blurs the line between this and being, well, himself.
- An episode of Evil Con Carne has General Skarr with a robot version of himself, who helps him usurp command from Hector. But by the end of the episode, the robot Skarr takes his advice of "Stabbing in the back and twist! Twist! TWIIIIST!" to heart, and manages to take command from him with a robot army. Skarr is very proud and happy of this... and then he's blasted by all the robots.