Fanfic genre based on the idea of giving one or more characters a child to raise. This is a common device for promoting a favored shipping (often slash), by showing how well the favored pair act as parents together. Sometimes the resident badass will be given a child to soften them (can be seen as somewhat related to Morality Pet) before pairing them with the hero.
In some cases the child may be another canon character, de-aged in some manner. In other cases, it can be the instantiation of an Intercontinuity Crossover, with a child imported from another story or series.
When one or more males are involved in the process, mpreg is always a possibility.
If this is canonical, it may be a Parents for a Day situation.
Add a few years, and you get Next-Gen Fic.
- All That Remains in which Tony Stark takes in the female clone of Captain America after the Marvel Civil War.
- Ice Cream Ice Cream by Ash Ai is a series of one shots that has Tony and Pepper raising their their little kid, Jared.
- The appropriately named fic, Xmen: Sabertooth Mpreg, is one of the rare kid fics that isnt warm and fuzzy.
- Calvin and Hobbes has lots of fics where an older Calvin has a son and/or daughter, often with Susie Derkins.
- So Wise We Grow is a Kirk/Spock Star Trek (2009) story in which the Vulcan Council locates Spock's son among the surviving Vulcans. Which would be great, except Spock's never heard of the kid before in his life.
- Another Star Trek (2009) is the Trust series; in which prior to his marriage to Spock, Sufficiently Advanced Aliens force Kirk to address his deep-seated trust issues by regressing into a troubled childhood. It's up to Spock and Kirk's elder brother Sam to help him get back to normal. Handles the subject matter more tastefully than one would expect, and includes social commentary on the TOS-canon Federation's system of term-marriages.
- Fanfiction.net has a Star Trek (2009) community dedicated to archiving de-aged fics, fic about the crew's childhoods, and childhood A Us. Mostly de-aged fic.
- Youngling, a Star Wars fanfic involving Anakin being de-aged to a three-year-old. Slightly more unusual in that Anakin remembers everyone and everything perfectly, but still has the mindset and emotional capability and the mindset of a (slightly-advanced) toddler.
- Yet another Star Trek (2009) example: The DVAS series. The full-length story focuses more on how the Deadly Vulcan Assassination Squad came to exist in the first place, but the side-stories are ridiculously adorable little tales featuring Jim, Spock, and the titular Squad - Selik the Adorably Precocious Child, T'Pralena the starship captain in training, and T'Lalia the Innocent Prodigy.
- The Zootopia fanfic The Violet Diaries is about Nick and Judy having a bunnyfox kit named Violet.
- In Take a Stand Nick Wilde discovers that he has a six-year-old daughter named Luna with one of his ex-girlfriends. Which complicates his relationship with Judy somewhat.
- Laume (on fanfiction.net) has written several kidfics for Harry Potter, including:
- A very well-written example would be Stealing Harry by Sam The Story Teller (link), which starts with Harry being raised by first the Dursleys and then Remus and Sirius (who open a bookshop near the Dursleys' house to keep a watch on him, then kidnap him after discovering he was being abused).
- This Harry Potter fanfiction, called Baby Project, is a perfect example.
- In the Leverage fandom on livejournal there's a somewhat common trend of de-aging the team's badass bruiser Eliot to be a small child and then sticking him under Nate's care.
- Considering the badass Spencer is? If someone competent works with it, it sounds like it could belong to Funny Moments. Bonus points if they manage to de-age Asberger's case Parker along with...
- Blessed Is His Child, a Supernatural kidfic, of all things that manages to be hilarious and heartbreaking within the space of a chapter! (pairings Dean/Cas, Sam/Gabriel and Crowley/Anna, as well as various OC pairings)
- Another Supernatural Kidfic series: The Adventures of John Gabriel Winchester, The Messiah. about Dean and Castiel's son. The pairings are Dean/Cas and Sam/Ruby.
- There are a LOT of House finding out he has a daughter to the point of the fans getting annoyed at them.
- The Lizzyverse, a Sherlock series, is about Sherlock and John's adopted daughter Elizabeth. It starts out with how they go about scaring off her boyfriends, and skips all over the age range after that.
- Getting Better is an AU in which both Sherlock and John are single parents, centred around the growing friendship between their children, Emily and Tristram.
- In this drabble, Sherlock's abused son shows up on their doorstep. No pairings.
- Another novel-length Sherlock kidfic is the Cinnamon 'verse, in which Sherlock has been raising his adopted daughter Imogen since before John moved in.
- The Nursery Files is an entire website dedicated to The X-Files kidfics from various couples in various categories.
- A few writers in the iCarly fandom write nothing but this.
- White Collar gets two with a de-aged Neal for Peter and Elizabeth to raise: One with him as a teenager and another with him as a toddler.
- There is a whole website dedicated to Stargate SG-1 and Stargate Atlantis kidfic, mostly of the deaged!character type: The Littleverse.
- Many Buffy the Vampire Slayer fanfics feature a character, usually Faith or Dawn, being de-aged and cared for by the other Scoobies.
- There are a few Homestuck fanfics based on this, such as "Cold Grublings". Made very convenient by the setting's local Applied Phlebotinum - "ectobiology", which allows an instant creation of a child which is a genetic mix of any two persons from anywhere and anytime (regardless of gender or age), without the need for actual physical contact.
- The universe introduced in Act 6 created a lot of these, as it had the four human heroes switching places with their ectobiological parents. Unfortunately, this never gets a chance to happen in canon.
- Thundercracker's Glory by Kenya Starflight is a Transformers: Generation 1 fic in which Thundercracker finds himself caretaker to his orphaned niece after his co-creation (sister) is killed. Shenanigans ensue.
- Past Sins with Twilight Sparkle as mother.
- As of September 20th, 2013, there's been no official word; any fic featuring Derpy Hooves with a daughter (or two) counts as this, at least technically. Even with how adorable they are together.
- Oddly popular in the Young Justice fandom for a while, usually involving Klarion turning someone(s) younger and forcing someone else to take care of him/her. (Alternatively, in a lot of fics Klarion turned people into cute animals for the same purpose.)
- Better Off Not Knowing is a sort of inversion of the concept, in which the biological daughter of two canon antagonists is Happily Adopted by characters with no connection to the main plot.
- Adopted Displaced is the Intercontinuity Crossover variety of this trope, seeing My Little Pony: Friendship Is Magic's Mane Six and others de-aged to babies and then sent to alternate universes to be raised by different parents.
- Parthenogenesis is a Where On Earth is Carmen Sandiego? fanfic from the POV of a now-retired Carmen's daughter, Marguerite. However, Carmen is a single mother and the identity of Maggie's father is never revealed to the reader.
- The More Than My Friend fanfic series is a Foster's Home For Imaginary Friends AU where Frankie adopts Mac after his family dies in an accident.
- Kijikun (on livejournal) has written several kidfics for Biker Mice from Mars, The Incredibles, Highlander, Due South, and Iron Man/Captain America.
- The Redemption Clause which follows the growing relationship between Buddy Pine and a adult Violet Parr, partly centered on Buddy Pine's adopted daughter.
- Harry Potter And The Invincible Technomage: A crossover one by Clell 65619 in which Tony Stark (and by extension, many of the premiere superheroes of the Marvel Universe) raises a young Harry Potter.
- The Son of Mine series on Fan Fiction.Net takes places in the Guyver universe, and gives Masaki Murakami a son.
- Common in Touhou doujins. Some of the more notable ones include Life of Maid and Mamange (Danbooru warning) as well as quite a few others.
- Marie is Coming is a story about Isabella's pregnancy with Marie Flynn.