This is a two-character dynamic that frequently shows up in fiction.
Somewhere in the Backstory, two male friends are making their way in the world as Those Two Bad Guys, keeping up the Masquerade for the Ancient Conspiracy, going to war for The Empire or doing hits for The Syndicate.
One day, orders come down from the top to Shoot the Dog. The "Outside" man pulls a HeelFace Turn and refuses to go along with it. They may have fallen In Love with the Mark, had his training wear off, or decided Even Evil Has Standards.
This moral awakening will prompt him to announce that he's leaving and ask for his companion to come with him. The "Inside" man will refuse, and his reason why will be reflected in his role in the series:
- He is unshakably loyal to the organization. He'll be The Dragon and is vulnerable to Redemption Equals Death.
- He feels staying is the best way to increase his own power. At some point, this type will overthrow the organization and take over as the Big Bad.
- He agrees with the objection, but feels that the only way things will change is if he can gain enough power within the organization.
At this point the "Inside" man will attempt to kill the "Outside" (with varying degrees of seriousness), but The Power of Friendship means that he can't quite go through with it.
Note: When listing examples, list the "Outside" man first.
- Inversion: Knives and Vash, Trigun The 'organization' in this scenario is the human race and Knives evidently honestly believes himself to be the good guy. He puts together a more typical evil organization later on.
- Variation: Akira Hojo and Chiaki Asami from the manga Sanctuary deliberately embrace this trope. Their plan to remake Japanese society calls for Hojo to rise to power as a Yakuza, providing under-the-table funding and "moral support" to Asami's career as a politician. (They played Janken to decide who would be who.)
- Basically the whole plot in The Magnificent Kevin comic books, with Kevin just being too damn scared to leave.
- Civil War was this on a large scale, with Captain America leading the Outside faction while Iron Man headed up the Inside. Officially, the pro-regs are Type 3 - trying to blunt Superhuman Registration from within - but there's a lot of Depending on the Writer and Alternate Character Interpretation here.
- Most movies that feature this are probably looking back to Logan's Run. Interestingly, in the book the inside man was secretly running La Résistance, which was why he couldn't afford to go AWOL. In the movie he just flips out and eventually gets dead.
- Pulp Fiction: the impetus for the change here is not the job itself, but the fact that the two guys escape being repeatedly shot at at near range. Jules, the outside man, takes this as a miracle and repents, deciding to give up the business and Walk the Earth. Vincent stays in, and is later killed by Butch. Since the film is in Anachronic Order, the moment of Jules' decision is treated as the finale though the "miracle" is at the beginning, and Vincent is killed in between.
- The Man-Kzin Wars books have two major characters who seem to fit this trope. Claude, Harold, and Ingrid are three friends in a love triangle who join the planetary defense force just before invading Cat-Like Aliens ultimately succeed at conquering their human colony and holding it for a generation. Claude and Harold get left behind by Ingrid during the confusion of the military evacuation; when Ingrid comes back decades later (and still young thanks to time-dilation) as part of a covert operation, she needs to tap them as contacts but both Claude and Harold have long ago abandoned active resistance: Claude has chosen to cooperate with the occupation forces and became their chief of police in the Capitol, while Harold started a nightclub there and became a big player in the criminal underworld. Naturally, they've fallen out with each other to the point of practically being nemeses. Both of them originally sought their positions in the belief that they could 'do good' through them, but by now have become largely corrupt. Both of them are also still very angry at Ingrid for abandoning them, but both of them are tempted by the possibility of regaining their integrity and throwing off their alien masters—who are all too happy to kill and eat suspected 'feral' humans. The resolution is quite tumultuous.
- Nicholas Easter and Marlee in the John Grisham legal thriller The Runaway Jury as well as in the movie version. Nicholas got himself planted as a jury member to influence a court decision involving large corporations (in the book it was a tobacco company and in the film it was the firearms industry). Marlee was on the outside interacting with lawyers on both sides of the case. Their motivations and MO differ in the two media.
- On Lost, Jacob and Smoke-Monster play out something like this after Smokey discovers the woman that raised them had actually killed their real mother
- In Nikita this is the dynamic between Nikita and Michael. Nikita rebels against Division when it kills her fiance while Micheal stays loyal as Percy's Dragon. To a lesser extant this also happens between Nikita and Birkhoff. They are good friends and Nikita wants him to join her in the fight against Division but Birkhoff is too scared of Percy. In season two they both join her, though Nikita's pupil Alex then takes over this dynamic.
- D&D 4th edition used this trope for their alignment system. Good characters are willing to overthrow corrupt governments, while Lawful Good characters prefer to change things from within.
- In Wicked, Galinda and Elphaba become this trope. They become good friends at school, but after they see the Wizard, Elphaba decides to work against him, and Galinda decides to work for him. At the end, they forgive each other and (sort of) reconcile their friendship before Elphaba has to fake her death and leave Oz forever. (In the book, she actually dies, and doesn't see Glinda so soon before it either, and the emotions are much murkier, less clear, and more mixed with bitterness on all sides.)
- Judges Drace and Gabranth in Final Fantasy XII. Not played straight though, as Gabranth only stays the inside man because Drace urges him to after her attempt to become an outside man ends in tragedy.
- Wesker and Birkin in Resident Evil, though they remained friends and comrades.
- Somewhat inverted in Suikoden II, where both the main characters essentially start out as outside men, with one slowly working their way into the system to subvert it from within. The trope follows from there, though, as there are multiple points where the outside man begs the inside man to leave the evil empire, the inside man eventually overthrows the original leader and becomes the one in charge, and the entire scenario ends with a Redemption Equals Death outcome. Well, unless you get the best ending, anyway.
- Denam and Vyce, at the end of chapter 1 in Tactics Ogre. If you refuse your orders, he goes off to follow them "because it's the only way to win the war", leaving the other troops to kill you while he does so, and you fight him later. If you obey your orders (for the same reason), you become the Inside Man, and you'll have to fight Vyce later under different circumstances.
- Right-Eye and Redcloak, from the Order of the Stick prequel book "Start of Darkness". Right-Eye leaves after deciding their leader Xykon is too dangerous to continue serving, while Redcloak believes he's already invested too much in The Plan to quit now.
- Adora and Catra in She-Ra and the Princesses of Power, respectively. Catra is a pretty textbook Type 2, knowing full well the Horde is using them but wanting to use it right back to gain more power for herself. She succeeds at the end of season 1, supplanting Shadow-Weaver as The Dragon to Lord Hordak.