The Stepbrother Sitch

The Stepbrother Sitch is a Kim Possible and Phineas and Ferb Crossover written by Owennumber1fan. The plot is pretty straightforward: Kim hears that Drakken is up to no good in Danville and heads out there with Ron & Rufus to stop him. However, a blown out tire on the Sloth causes them to stop for help at a familiar house; Hilarity Ensues.

The story proved to be popular enough that the author wrote a sequel Fan-tastic Voyage. In this one, Phineas, Ferb & Candace come to Middleton to pay Kim a visit; the teen hero must deal with Drakken & Doofenshmirtz's newest plan, as well as contend with Candace acting like a crazy fangirl.

Those two stories were followed by The Life of Riley, a Kim Possible and The Replacements Crossover set a few days after the aforementioned story, where Kim visits Pleasant Hills and discovers one of her old foes has a connection to Agent K; Kim Goes Hawaiian^{[dead link]} in which Kim and Ron decide to go on vacation following the events of the last two stories, and meet up with Lilo & Stitch (this story poses that the original crossover between the two was Canon; Wikipedia says otherwise). And Phineas & Ferb's Excellent Adventure in which the Darings' travel to Danville to accept an award for Riley; K is revealed to have a past with Linda, and an old enemy is up to no good. The last 2 stories mentioned are currently in progress.

The stories may be considered So Okay It's Average or Pandering to the Base, but are favorites of many on Fanfiction.net.

Tropes used in The Stepbrother Sitch include:

Actor Allusion: After receiving a phone call from Candace in Fan-tastic Voyage Kim initially mistakes her for her old foe Camille Leon, both of whom are voiced by Ashley Tisdale.
Affectionate Parody: In The Stepbrother Sitch, Phineas gets the inspiration for his big idea after watching Priest.
Amusing Injuries: Shelton gets this in The Life of Riley when he re-activates Dementor's time bomb
Author Appeal: Except for the two most recent ones, all the stories have featured a lady bound and/or gagged.
Big Bad Duumvirate: In the first two stories, Drakken & Doofenshmirtz of course, and Kim Goes Hawaiian has one in the form of Professor Dementor & Dr. Hamsterviel
- Has now been upgraded to a triumvirate as Phineas & Ferb's Excellent Adventure has Dr. Scorpious, the Regurgitator, and Khaka Peu Peu all working together.
Brainwashed and Crazy: This happens to Perry in Fan-Tastic Voyage and Riley in the Life of Riley
Canon Fodder: The stories offer their own explanations for what happened to Riley and Todd's parents ( died in a car accident) what happened to Phineas & Candace's dad ( he walked out on them) and even poses a theory as to why Drakken rarely uses syntho-drones.
Continuity Porn: Nearly every story features references to past episodes of the shows, perhaps too many for some's tastes.
Deus Ex Machina: In The Life of Riley, the fact that the HenchCo brainwashing helmets can be undone with The Power of Love although it can fall under Rule of Funny.
Does Not Understand Sarcasm: This exchange from the Life of Riley:
Does This Remind You of Anything?: Kim & Ron's actions at the beginning of the Stepbrother Sitch.
Funetik Aksent: Professor Dementor has this is the Life of Riley and his reappearance in Kim Goes Hawaiian. Averted in the latter by Dr. Hamsterviel though, as two characters with that kind of accent would be hard to keep track of.
Hilarious in Hindsight: In Agent K's flashback to her first battle with Professor Dementor in the Life of Riley, it's revealed he used to be a Dr. Doom-inspired villain, but was forced to change to his current persona thanks to lawyers from Marvel. Now Disney owns Marvel (although the author will admit he thought of that idea before it was announced that Disney had bought the comics giant).
Incredibly Lame Pun: Most of the titles of the stories, as well as the respective chapters.
Insistent Terminology: In The Stepbrother Sitch, Shego grabs Isabella and threatens to "fry the Girl Scout" unless Kim & Ron surrender. Isabella then angrily reminds her captor that she's a Fireside Girl, not a Girl Scout.
Lampshade Hanging: Due to the shows that are in these stories, this is inevitable.
- A good example: In Phineas & Ferb's Excellent Adventure, Candace is spying on her brothers from her room, then asks Riley, who she has reluctantly been forced to share her room with, what's she reading:

"Anne of Green Gables. It's about an imaginative redheaded orphan who gets adopted by a cool couple and has adventures. For some reason, I can really relate to her."

Let Us Never Speak of This Again: Kim says pretty much those exact words to Ron in Fan-tastic Voyage after she gets beaten by the brainwashed Perry.
Loony Fan: Candace comes off as one of these in Fan-tastic Voyage (hence the title), even going so far as to buy clothes that look exactly like Kim's.
Mama Wolf: As shown in the Life of Riley, when Agent K threatens Professor Dementor when he reveals his plans for Riley.
Never Live It Down: In The Stepbrother Sitch Vanessa agrees with Shego that Drakken has the worse plans when she brings up his mind-control shampoo gambit. In the sequel, Shego mentions it to him again, and he agrees that it was a stupid idea.
Noodle Incident: What happened when Ron tried surfing in Kim Goes Hawaiian. Word of God is that the author was originally going to write that scene, but then decided it would be funnier if it was left to the reader's imagination.
Original Flavor: And how!
Pandering to the Base: People could see the stories as this.
The Power of Love: Agent K uses this in the Life of Riley to break the brainwashing on Riley.
Running Gag: In the Life of Riley, Dick is led to believe that Kim is a crimefighter/pop star and keeps making references to said career throughout the story.
Tempting Fate: In Phineas & Ferb's Excellent Adventure, Tasumi says she likes going on trips with the Darings, because they get into all kinds of wacky adventures. Riley responds that they don't always have adventures...