Interesting question. As it happens, my second gateway into fanfic was through Kim Possible, and that fandom is noteworthy for supporting two very different OTP pairings: Kim/Ron (aka K/R), and Kim/Shego (aka KiGo), with large bodies of work built up in both camps long before the 4th season of the series canonized the K/R pairing. What I discovered was that if the writer did a sufficiently good job of extrapolating a given characterization from what we saw on the screen, I could enjoy works from both camps. Three examples (all on the long side, but note that in two of the three cases, I'm giving you works outside the relevant author's longest/best-known series). Just as further anomaly: all three of these recs are for stories by male authors, and that's broadly representative of the demographic for KP fanwriting, or was when I was active therein a decade or so back now....
An Unacceptable Sitch, by Allaine First in a series that grows into KiGo, featuring both strong characterization and skillful plotting.
The Code of the West, by King in Yellow This author is best known for a strongly characterized, wide-ranging KiGo series ("Best Enemies") that has been evolving for a decade now, with dozens of stories extending to well over a million words. This new story, though, is self-contained, stars Shego, and develops a pairing that I don't think anyone else in the fandom had even begun to contemplate before this summer.
Kim Possible: The Next Generation, by MrDrP Yes, this is a fusion of ST:TNG and Kim Possible, essentially dropping the KP characters into the TNG continuity. Yes, it's almost 200K words. But darned if it doesn't do a first-class job of integrating its material, and building a solid K/R relationship story at one and the same time. (I could have pointed you at MrDrP's "Epic Sitch" stories, a mainstream KP series also developing the K/R pairing. But while that one's not as sprawling as the "Best Enemies" cycle, the overall word count is still, well, epic.)
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An Unacceptable Sitch, by Allaine
First in a series that grows into KiGo, featuring both strong characterization and skillful plotting.
The Code of the West, by King in Yellow
This author is best known for a strongly characterized, wide-ranging KiGo series ("Best Enemies") that has been evolving for a decade now, with dozens of stories extending to well over a million words. This new story, though, is self-contained, stars Shego, and develops a pairing that I don't think anyone else in the fandom had even begun to contemplate before this summer.
Kim Possible: The Next Generation, by MrDrP
Yes, this is a fusion of ST:TNG and Kim Possible, essentially dropping the KP characters into the TNG continuity. Yes, it's almost 200K words. But darned if it doesn't do a first-class job of integrating its material, and building a solid K/R relationship story at one and the same time. (I could have pointed you at MrDrP's "Epic Sitch" stories, a mainstream KP series also developing the K/R pairing. But while that one's not as sprawling as the "Best Enemies" cycle, the overall word count is still, well, epic.)