- In To Hell and Back (Arrowverse), Malcolm learns that Oliver is his biological son in Chapter 25. Oliver would learn of this in Chapter 158 from Ra's al Ghul.
- In "Dark Secrets
", Cheetor learns that, after years of believing his parents were killed long before the Beast Wars, not only is his mother alive, but Optimus Primal is his actual father; his mother left without telling Optimus of her pregnancy because she was aware of a prophecy that Cheetor would defeat a ruthless Transformer with special powers.
- The Bolt Chronicles: Lampshaded by Blaze in "The Cameo" when he realizes that he's Bolt's father, even using the commonly misquoted version of the line. The younger dog not surprisingly misunderstands what his father means, asking Blaze why he just called him Luke.
- In the fanfiction Right Beside You, the Beldam captured Wybie and now Coraline and the Cat had to enter in the the Other World to rescue him and there, Coraline learns that Wybie's true father is the Cat, actually named Richard. The Beldam killed his mother and transformed his father in a cat. Although it's based on a Wild Mass Guessing, it works very well.
Crossovers
- In The Great Dog Detective, a crossover fanmake/Film Fic of The Great Mouse Detective, Fat Cat of Chip 'n Dale: Rescue Rangers reveals to Garfield that the former is his father, much to the latter's dismay.
- In Yugioh The Thousand Year Door Redux, Vladmir, the Shadow Spawn of Darkness and the heir of the Empire of Shadow, is the son of Count Bleck.
- In canonical Sailor Moon Chibi-Usa is the daughter of Usagi and Mamoru. In Ranma ½ crossover Fist of the Moon there're hints that her parentage is different, but it isn't until Ranma goes down and Usa screams "Mommy!" that it's made obvious. She later refers to Usagi as "Pops," foreshadowing the blonde's Jusenko boy curse.
- In Earth-27, Deathstroke is Ronin and his brother Sam's biological father.
- In Chapter 81 of BlazBlue Alternative: Remnant, Ragna learns that Professor Ozpin is his father via the flashbacks and memories he has of his past life as the Black Beast.
- In A Cure for Love, V is an Original Character Action Girl who is later revealed to be the Big Bad is also revealed to be Mello's mother. She wasn't there for him growing up because Wammy's House wouldn't let her near her son, deeming her "too broken to fix" and so trained her to be an assassin instead.
- In Zero 2: A Revision, Original Character Shaun confesses to Tai and Sora that he is in fact their Kid from the Future, who has traveled back in time to avert a Bad Future he inadvertently helped cause.
- Having been adopted by Julieta and Agustín after her failed gift ceremony in La polilla y la mariposa, Mirabel doesn't find out that her actual parents were her Tío Bruno and Tía Anná until after the collapse and reconstruction of Casita Madrigal.
- In The New Retcons, Elly Patterson is Claire Thompson's biological mother, who was forced to give her up for adoption.
- In the fanfic, Frozen Hearts (Sakume), while Hans is trying to return to Arendelle, he and his brother Heins run into some pirates, and, after a while, recognize their captain as their brother, Heinrik. Later that chapter, and that day, they encounter Harry, who ran away from home and serves as a fence for Heinrik.
- The Queen of Hearts revolves around Elsa trying to find out if she's a Chocolate Baby or not. It turns out that her parents couldn't conceive their first child, so they found a man to act as a sperm donor. Along the way Elsa and Anna find out that Hans is their half-brother from when their mother was imprisoned during a war with the Southern Isles. Hans doesn't know of their relationship.
- In The Indecipherable Riddle, Harry discovers he was kidnapped by James and Lily Potter as a baby (and that they fed him dangerous potions so they could pass him off as their own son) and that his true parents are Voldemort and Bellatrix Lestrange.
- Lampshaded in A Rose and a Thorn 3.Ashura: I am your father Luke — I mean, Shadow.
Shadow: Shut up with the clichés already! You're not actually my biological father, are you? I saw that movie. I'm not going to do that stupid NOOOOOOOOOO thing.
- In For the Glory of Irk, it's established that Irkens don't do family units, but that genetic samples are usually taken from donors and used to create new smeets, with varying levels of anonymity. Because of this, Vero and Xia (and later Ven) know that Tallest Red is one of their donors, but don't know who the other one is — and thus it's a massive surprise to Xia when she learns that said donor is Zim. Being a Consummate Professional (and an egomaniac), she's horrified and disgusted to learn this, because of how idiotic and destructive he is.
- In the fanfic It's not the Raptor DNA, John Hammond is the father of Elise (an AU Indominus Rex that has human DNA).
- In the fanfic Keys to the Kingdom, Master Xehanort is Sora's paternal grandfather.
- In The Lion King Adventures, it's revealed in Series 3 that Hago — Simba's Arch-Enemy — is actually Nala's father.
- Near the end of MGLN Crisis, Fate takes a DNA test and finds out that her father is actually Clyde Harlaown. One of the stories in Red Jewel Diaries has her looking deeper into it and discovering that it was actually an aged up clone. Seeing as she was already related to Clyde due her adoptive mother Lindy being his widow, it doesn't change anything other than give her closure.
- During Megane's cameo in Infinity, it is implied that Zest is Lutecia's father via a one night stand. The established timeline of events also implies that she never got the chance to tell him before his death and her falling into a coma.
- Miraculous: Marinette's baby: Much of the story has Marinette unwilling to tell her parents who the father is (mostly because she was not sure who Chat Noir was).
- A very common Fandom-Specific Plot is the reveal that Izuku's father is All For One. The fact that Izuku's actual father is The Ghost, combined with Kohei Horikoshi's love of Star Wars and All For One's Darth Vader-esque appearance really, really helps the popularity of this trope.
- Crimson and Emerald: If you even read the tags on the story, you know that this is another All For One is Midoriya Hisashi fanfics.
- Conversations with a Cryptid, Izuku's father is Hisashi Midoriya (and this is his real name), but it's not until the end of the story that other characters connect him with the alias he's been using most of the time, All for One.
My Little Pony: Friendship Is Magic
- Twillight Sparkle's awesome adventure: Inverted; we go through the whole story thinking Celestia is Twilight's mother, but then at the very end her brother's ghost tells her that it's not actually true, and in fact she killed Twilight's real parents.
- Pony POV Series: Discord reveals to Diamond Tiara that she and her mother are direct descendants of his mortal mother Shady note , making him her great-great-something uncle.
- In Princess Trixie Sparkle, the main antagonist reveals to Luna that she's her older sister. Astelle is a Fallen Hero who was already an adult when Luna was born. Celestia hid her existence from Luna for several thousand years.
- The Equestrian Wind Mage:
- The Equestrian Wind Mage has a non-villainous example during Season 2, when Daring Do reveals that she's Rainbow Dash's mother, having abandoned her with her father as a newborn, out of fear of not having what it took to be a parent. Dash chews her out for this, but her anger burns itself out, and they reconcile.
- Season 3 reveals that Dethl is Vaati's father. Though this was heavily foreshadowed in the previous season, and straight up spoiled in the Universe Chronology.
- In How I Lost My Mother, Princess Celestia is revealed to have been the mother of Cozy Glow, and details that her daughter's Start of Darkness was because of a prophecy foretelling that Cozy would destroy Equestria: a prophecy that ended up being Self-Fulfilling since it was Celestias' own hasty decision to erase all knowledge of Cozy Glows' existence and denying her access to her family that caused Cozy Glow to turn to hating her mother and serving the prophecy of "destroying" Equestria based on what would happen should any knowledge about the truth were to be revealed and how it would destroy the publics' image of Celestia as a wise and just ruler instead of a control freak.
- The Pieces Lie Where They Fell: Variant — chapter 26 of the sequel, Picking Up the Pieces, reveals that as she was dying at the hooves of Prince Blueblood, Chrysalis revealed the identity of her child's father — Shining Armor — to him. Their identity (coupled with Would Not Hurt A Child) is why Blueblood spared the infant.
- Inverted during the time travel arc of Vapors. Minato quickly guesses that Naruto is his son, but it takes much longer for him to realize that Aiko is being snippy because she's his daughter and has abandonment issues.
- 2003's Bloodlines (The SOC Puppet) begins with the Fourth Hokage revealing to Naruto that he's his father. This was years before it was revealed but canon, but fans already knew this (and an author's note in Bloodlines lampshades the obviousness).
- The Line Is Not Broken is a oneshot based on the theory that Tsunade is Minato's mother (and as a result, Naruto's grandmother). Tsunade had a One-Night-Stand Pregnancy after a drunken fling with Jiraya. Jiraya never knew about the baby.
- A Father's Wrath instead of Minato, Naruto's father is Orochimaru
Percy Jackson and the Olympians
- In Whispers in the Dark, a popular Percy Jackson and the Olympians fanfiction, Luke pulls a "Taylor, I Am Your Father."
- There are tons of Pokémon: The Series fanfics that imagine the Team Rocket leader Giovanni as being Ash's father. But many other theories exist. Since the 8th movie, for example, some writers have attributed Ash's aura to him being the son of Sir Aaron, or at least one of his descendants. This also extends to Ash's game counterpart, Red.
- In the one-shot Severance, it's revealed early on that Ash's father is Giovanni. When Delia worked with Team Rocket, she had a one-night stand with Giovanni that resulted in Ash. Ash himself doesn't know. The story starts with Delia having been shot after she tried to kill Giovanni. Giovanni knows that Ash is his son... he just doesn't care and is out to kill him and Delia.
- The Oak/Delia oneshot Sins of the Past has Delia as an ex-Rocket member. Ash is Giovanni's biological son, but she never told her deceased husband, her son, or Giovanni.
- Frayed Ends has Delia having half-lied to her son about his father. She told Ash that he's away pursuing his dream, but left out the part where "his dream" was "being a crime boss".
- Subverted in the oneshot Revenge. After Ash defeats him, Giovanni has most of Ash's loved ones brutally killed one-by-one. With only Misty left, the two run off together but end up meeting face-to-face with Giovanni anyway. Giovanni tells Ash that he is his son, but that doesn't stop Ash from shooting him. It later turns out Delia is safe. When Ash questions her on his father, she confirms that Giovanni was mistaken and that he wasn't Ash's father. Ash's dad was some random guy named "Fred" who helped Delia leave Team Rocket as a teen.
- In the Pokémon fanfic The Road You Choose, the final story not only reveals that Ash's biological father is Pokémon Master Red, but also reveals that Jessie of Team Rocket is actually Giovanni's daughter, and Ash's Sinnoh companion Dawn is his half-sister as a result of Red having an affair with Dawn's mother after he left Delia; Jessie's family ties to Giovanni are the reason her team has ever been fired despite their mistakes, and characters such as Iris note that Ash and Dawn being related actually makes perfect sense in hindsight.
- In Mended, a 19-year old Ash finds out that Professor Oak is his father and that his supposed father walked out before he was even conceived. He initially takes this poorly and gets drunk, but later comes to terms with it.
- In Lost, Delia reveals to Oak that Ash's father is none other than Team Rocket's leader Giovanni. When Delia learned just what Giovanni's "family business" referred to, she left him. Giovanni doesn't even know about Ash. Delia made up the excuse about Ash's dad being on a Pokémon journey as a cover-up. When Giovanni turns up for the memorial service (due to the TR trio being on the ship), Delia reveals to him that Ash is his son.
- Back to Zero is a fanfic where Giovanni is not only Ash's dad, but he's also Jessie's dad. This unknowingly makes Ash and Jessie half-siblings.
- Chapter 23 of Pokémon Reset Bloodlines has Ash confront the local Knight of Cerebus, Belladonna Tyrian, who quickly notices the resemblance between them, and realizes they're half-siblings. Moreover, this revelation quickly drops the bomb that all those Ash-lookalikes our hero has encountered before are related to him, having all been sired by the same father.
- In Speak Up, Giovanni, the leader of Team Rocket, is Red's father. The author got this idea from Pokémon Live!.
- In the seventh chapter Dark Secrets, Giovanni accidentally lets it slip that he is Jessie's father.
- Guardian of Light: While the story had been placing hints and a few readers had already guessed correctly, the reveal that Pitch is Helen's biological father still took many by surprise. The scene is an obvious Shout-Out to Star Wars, but the author denies watching the film while working on the chapter.
- Rosario Vampire: Brightest Darkness Act II reveals that Kurumu's father is none other than the Lord of Hell himself, who conceived her with Ageha during a one-night stand; Kurumu herself remains unaware of this.
- In RWBY: Scars, Ruby asks her Honorary Uncle Qrow why there are so many discrepancies in what she's heard about past events. She ends up pushing him into revealing to her that he's her biological father, not Taiyang. Years ago, Summer left Qrow and it was decided to raise Ruby as Taiyang's daughter. Ruby reacts poorly and runs out the room.
- In Empath: The Luckiest Smurf, though Empath knew that he came from the Smurfs, what he didn't know until his 150th birthday is that he is Papa Smurf's only biological son, while the rest of the Smurfs were Happily Adopted. This of course makes Brainy Smurf upset, because he always assumed that he was Papa Smurf's only biological son. (He turns out to be Empath's illegitimate half-brother through the same mother.)
- In the Star Trek: Voyager Parody Fic "Man of Wood" by Odon, an explanation for the canon Crack Pairing of Seven of Nine and Chakotay is found when the latter discovers during a Vision Quest that his father is producer Rick Berman. He responds with the appropriate Big "NO!".
- Plan 7 of 9 from Outer Space. Dr. Zarkendorf brags that he's been some of the most evil men who've ever lived, including this trope."NOOOOOOOO!" screamed Buster. "That's impossible! You've ripped off George Lucas!"
"That's right, you wet-nosed weenie: I AM YOUR FATHER!"
- The "Pathways" series involves Obi-Wan discovering that the Anakin who became Vader is actually a clone, managing to rescue the original Anakin while working to protect Leia. Having escaped the clone, Obi-Wan takes Anakin and Leia to Tatooine, where he introduces them both to Luke and confirms Anakin's guess about his true relationship with the children, although the family agree to remain separate to avoid detection from Palpatine and the clone.
- In Sonic the Hedgehog: Erazor's Revenge, it is revealed (by the author) that the evil Genie of the Lamp, Erazor Djinn is the father of Sharah the Genie of the Ring, the lesser genie.
- In the climax of Sonic X: Dark Chaos, Maledict reveals that he is the creator and father of both Shadow and Sonic (and Eric as well). They were all early prototypes of Maledict's "Ultimate Weapon" project. None of them worked out; Gerald Robotnik turned on Maledict and altered Shadow, Sonic's fetus failed and Satan launched him out of a capsule to euthanize him, and Eric was literally flushed down the sewer after a catastrophic failure did... something to him.
- In The Birthday Present, Nightwing meets Starfire's children Mar'iand'r and Jakand'r, and, noticing that their ages line up with when he and Starfire were last together before she had to return to Tamaran, he does a DNA test which confirms he's their father. He doesn't tell them, however, knowing that they wouldn't believe him. Instead, he waits for Starfire to arrive on Earth and she tells the twins the truth of their parentage.
- Very common in Xenoblade Chronicles 3 fics. Even pre-release, several characters were theorized to be the children of the heroes of the previous games. Therefore, it's very common to find fics where the characters discover this, with the various quirks of Origin allowing them to meet their predecessors.
- Mio is pretty much universally assumed to be Nia's daughter, to the point that it's probably harder to find a fic where this isn't true. The game itself strongly implies it to be true.
- Sena shares Brighid's burning hair, so she's usually assumed to be the daughter of Brighid and Morag.
- Ashera is often treated as the daughter of Sharla and Reyn, with Dunban's training to explain why they fight the same.
- On the Crack Fic side, Eunie is often portrayed as Melia's daughter (they're the same species, and that's the only connection), while Isurd and Cammaravi sometimes show up as Mythra and Pyra's sons (they're the only Light and Fire Blades in the game). One in particular that gained a few fanfics was Noah being Melia's son (and Eunie's twin brother), despite them not being the same species. There's no sign of this in the game, but they do have a handful of minor connections that are not explained in game, and which some fans decided to spin off into a mother/son relationship.
- The Big Bad of Born to Be Wilde who has been going around killing every crime lord in Zootopia? Nick initially suspects he's one of his old con victims seeking revenge on him. He is actually Nick's dad, seeking revenge for Nick by killing those who refused to take him in after he ran away from home, and Mr. Big for throwing him out again. Nick does not take this well.
