Kigo

"Like you can even handle Kimmy without me. [...] I'm not going to let this thing just walk in and destroy Kimmy."

- Shego Kigo is the femslash ship between Kim Possible and Shego from the Kim Possible fandom.

Canon
Kim and Shego are rivals, and the first time they meet each other, it's during a fight in a skiing place. Although both of them are always in battle, they never actually cause each other any serious damage and they have mutual respect for each other. This is why Shego goes as far as to save Kim's life, several times (in In "Go Team Go", saving Kim from Avarius; in "Mad Dogs and Aliens" saving Kim from Warmonga; in "Stop Team Go" saving Kim from Shego's own brothers). When Earth was under attach by the Warlodians, Shego   attempted to team up with Team Possible, only to find out that Kim was captured along with Drakken. Despite the fact that Shego's hands with her power can easily go through metal, or even bust through a cave wall, whenever she pins Kim down, she never causes her any serious damage.

Despite the fact they're both rivals, they show great deals of care for each other, playfully teasing each other and even addressing each other with pet-names. Particularly from Shego's side. Shego has tons of pet names with which she addresses Kim, such as Pumpkin, Princess, Sweetie, and her most used one, Kimmy. And Shego has also been the only person to be the most vulnerable to Kim's characteristic puppy-dog pout, not even trying to fight her and instead immediately giving into her wishes. Like in the series' finale when Kim asks her to clean the mess left in the fight against Warmonga and Warhok, for her to have her graduation. She makes her puppy-dog pout and Shego instantly falls for it.

In Season four's episode, "Stop Team GO", after Shego is "turned good" by the "Attitudinator", she spends all of her time with Kim, being really close with her. Kim spends so much time with Shego that she forgets about her spy responsibilities and starts getting Ron jealous. Kim gives Shego a ride to school at the beginning of the episode and Shego immediately hugs her as soon as they get down from the car, thanking her for "everything". Then, both of them go shopping and to a dinner date, even roller skating. After Shego gets turned back to normal by Ron, she grabs Kim's shoulders and says "I couldn't tell you this when I was evil, but...", getting abruptly cut by Ron zapping her back to "normal". Shego says goodbye to Kim with a "next time Kimmy", and afterwards, she's seen fondly and nostalgically staring at some pictures she took with Kim at a photobooth, quickly hiding them when she sees Drakken approaching.

In Season four's episode, "Mad Dogs and Aliens", as stated, Shego saves Kim's life once again. Kim was being brutally beaten by Warmonga. And right when Kim was going to almost fall unconscious in the ground, Shego breaks from the chains she was bound to, confronting Warmonga. This is significant as well since Drakken tells her that he was about to snatch victory, which Shego refued to allow anyone but herself to take down Kim.

It is known that Kim is around the age of 14-17 during the shows run, while Shego is in her 20s (although it has been said that Shego's age has been kept vague on purpose).

Behind the Scenes
During one of the episodes of Christy's Kitchen, a cooking show by Kim Possible's voice actress, Christy Carlson Romano, she invited Nicole Sullivan, Shego's voice actress, and while they cooked they also discussed the Kigo ship. Christy talked about how she wished Kim and Shego would've stayed close friends as they've been in the "Stop Team GO" episode, to which Nicole replies that she agrees because she realized there how similar the two of them are. Afterwards, Christy talked about the people who ship Kigo romantically and asked Nicole "do you think that they would have a successful non-toxic relationship?", referring to Kim and Shego's constant fights throughout the show. So Nicole answered: "I don't think Shego is capable of having a non-toxic relationship. I think she loves to love and loves to hate."

Fanon
Kigo is one of the most popular ships within the Kim Possible series. People ship these two characters for many reasons, but most importantly because of the incredible chemistry between the two that Kim doesn't even have with Ron until the last seasons. Many fans started noticing how "flirty" their fights seemed, as Shego would address Kim by all types of pet names, such as "princess" and "pumpkin". The fans were also quick to note how compatible the two were, which was also expanded on in the series with both characters' backstories being greatly expanded. Shego was revealed to be originally part of a family of superheroes, which led to many fans imagining a world where both Kim and Shego work together. This was shown in the series when Shego was mind-flipped and "became good", and many fans started mentioning how in an alternate universe, if Shego was good, the two of them would be girlfriends. Fans also imagine an AU where Kim turns evil and joins Shego. All of the possibilities that AUs gave to fans (even one where Kim and Shego formed a family together ), made this ship even more popular among fans of the series. The two characters were also drawn together narratively. Shego desperately wants to be the one to up Kim in a battle, and Kim wants to be a worthy foe for Shego. And yet the two can have banter with each other that often comes off as fond, and can even spend adorable moments together, as seen in the "Stop Team GO" episode. Visually, the two characters complement each other as well, with their complementary color palettes and contrasting aspects of their personalities that fit many tropes that fans love, such as light and dark and bubbly and solenm.

To this day, there are still dedicated Kigo shippers who write fanfiction of the two characters in the canon universe, or in alternate universes. Out of the 950 works in AO3 in the Kim Possible fandom, 380+ are Shego works, making it the most popular pair, only followed by Kim x Ron fanfiction, with 268+ works up until this time.

Fandom
FAN FICTION