The Hyde Factor is a Kim Possible fanfic by Erin Mills, in which strange things start happening to Kim after she accidentally gets injected with something during a mission to retrieve a stolen notebook. It turns out that the notebook originally belonged to Dr. Jekyll, and the injection is causing Kim to repeatedly transform into an evil alter ego (who takes the name "Faye Morgan").
Kim attempts to make the best of the situation, even trying to be as fair as she can to Faye without letting her hurt people. Unfortunately, it turns out that the transformations are unstable; either Kim's body will stabilize in one configuration (possibly turning her into Faye permanently) or the repeated stress to her system will kill her. Worse, Global Justice finds out about Faye, and the people who pull GJ's political strings have their own plans for her....
This story provides examples of:
- Adaptational Villainy: Will Du is all too willing to help ICAD One with their evil deeds.
- Battle in the Center of the Mind: The final confrontation between Kim and Faye.
- Berserk Button: When Ron tries to capture Faye in order to make one last-ditch effort to save Kim, she gets the better of him... until she tells him that she's going to kill his friends and family, concluding with Hana. Cue full-bore Mystical Monkey powered ass-kicking.
- Broken Pedestal: The events of the story leave Kim with a lot less respect for Dr. Director and Global Justice.
- Crazy-Prepared: Faye has the foresight to bribe DNAmy (the only person to know the Hyde serum's formula) to not help Kim... with a rare Cuddlebuddy with vials of Faye's blood hidden in it.
- Darker and Edgier: Obviously, with a Government Conspiracy using Global Justice as a tool for its Dirty Business so that they can gain control of a brutal sociopath, presumably for the purpose of using her as a weapon.
- Dirty Business: After ICAD One orders her to capture Kim, Dr. Director reluctantly obeys, considering that a lesser evil than having ICAD One take over the operation directly (which happens anyway).
- The End... Or Is It?: DNAmy has some hidden vials with blood samples from Faye that might enable her to re-create the transformation forumla.
- That said, the author's notes at the end of the story say that no sequel is planned.
- Et Tu, Brute?: After the crisis is past, Kim firmly calls out Dr. Director for selling her out and allowing Global Justice to be corrupted.
- Eye Color Change: Kim's green eyes change to violet when Faye is in control.
- Find the Cure!: The main goal of Kim and her allies in the story is to find a way to stop her transformations into Faye from occurring.
- Gilligan Cut: After assuring Kim that he can handle anything Hana dishes out by himself, it cuts to him freaking out as she produces a magical fireball and nearly throws it at him.
- Godzilla Threshold: With Ron, Wade, and Kim and Ron's families being held hostage and unlikely to be released alive, Kim allows Faye to take over completely.
- Hired to Hunt Yourself: On behalf of his son, Señor Senior Senior asks Kim to find the person responsible for putting Bonnie in the hospital... and turn the culprit over to him rather than the authorities.
- How We Got Here: The first chapter is a scene from fairly late in the story — Kim transforms during a fight with Shego, after which Ron finds Shego beaten nearly to death and a flippant note from Faye. The next chapter is set three months earlier, and describes the mission in which Kim gets injected with the transformation formula.
- Jekyll & Hyde: Referenced in-universe; see the A True Story in My Universe entry.
- Just Following Orders: Will Du's attitude when ICAD One removes Dr. Director and puts him in charge of Global Justice.
- Loophole Abuse: Kim is able to get Faye to agree not to kill anyone, and to leave certain people completely alone. There are a lot of nasty things you can do to someone without killing them, and Bonnie isn't on the off-limits list....
- Metaphorically True: Without quite saying so, Kim gives Señor Senior Senior the impression that she killed Faye.
- Mugging the Monster: Bonnie makes the mistake of hassling Kim just as Faye is about to take control.
- Noodle Incident: Apparently, one time, Ron tried to keep Hana in line with a baby harness attached to the sofa, but instead, Hana ended up dragging it along with her, smashing it up.
- Power Dyes Your Hair: Faye's hair is a dark shade of red instead of Kim's red-orange hue.
- Save the Villain: When Faye takes control during a mission, Ron does some fast talking to convince her not to kill Duff Killigan.
- Shout-Out: Apparently, Global Justice's recruitment and training practices were based on the methods pioneered by one Hunter Gathers.
- Split-Personality Merge: When Kim's mind and body stabilize after her final internal struggle, she retains some of Faye's enhanced strength and senses. The final scenes indicate that, while she's basically back to her old self, her personality has become a bit more tough-mindednote and hedonisticnote
- Split-Personality Takeover: Faye regularly take over Kim's body.
- Stop, or I Shoot Myself!: Faye threatens to kill herself (which would of course also kill Kim) if Kim tries to cure the transformations.
- Superpowered Evil Side: In addition to being more ruthless, Faye is significantly stronger than Kim. Faye also has extremely sharp senses.
- Talking to Themself: Kim and Faye originally communicate via recorded messages; later, Faye is able to remain awake and hold an internal conversation when Kim is in control.
- The Tape Knew You Would Say That: When Kim leaves Faye a video message outlining her rules, Faye retorts sarcastically that Kim doesn't trust her. Kim on the video then says "No, I don't".
- Theme Initials: Averted. When Kim's alter ego realizes that she needs her own name, she specifically rejects "that idiotic 'different name, same initials' crap".
- A True Story in My Universe: When Ron asks Lord Utterson for more information about the notebook he'd asked Team Possible to recover, he explains that The Strange Case of Dr. Jekyll and Mr. Hyde was based on events in which his great-grandfather (the "Utterson" of the novel) was involved. The notebook was Dr. Jekyll's, and had been in the Utterson family's possession until DNAmy stole it.
- Undead Tax Exemption: Justified. Wade creates a separate documented identity for Faye, as part of Kim's effort to keep Faye's existence secret and to persuade Faye to accept some limits on her behavior.
- Villain: Exit, Stage Left: When Faye escapes and starts mowing down GJ agents, ICAD One bugs out.