Characters making an Early-Bird Cameo in Fan Works.
Crossovers
- Child of the Storm has a blink-and-you'll-miss-it reference to Doctor Essex in chapter 40, who later shows up in the sequel Ghosts of the Past, established as the sinister presence who kept Harry at Privet Drive.
- In The Great Starship Battle, the Twelfth Doctor has one line even though the story was written before the contributors knew who would be playing him.
- In Kings of Revolution, Ginga (and Subaru and Teana later on) gets introduced earlier than the original Nanoha timeline.
- Last Child of Krypton:
- Asuka travelled to Japan right after the death of Sachiel.
- In both the original story and the redux, Kaworu shows up early on.
- Pokémon Crossing: Lechonk appears in the Hoenn region in chapter 36 before Pokémon Scarlet and Violet released.
- Star Trek: Phoenix:
- Zhidar first appears in the story's first chapter as the antican security guard whose beard Sunset sets on fire during her initial panicked flight through San Francisco. He has a couple of non-speaking reappearances, but drops out of the story after the end of the chapter. He returns in the opening of Season 2 when he's recruited as the Phoenix's Chief Security Officer, a role he retains afterwards as a recurring member of the supporting cast.
- Dr. Selar makes a brief appearance in the first chapter as the doctor who examines Sunset after she returns to consciousness. She returns late in Season 2, having been assigned to the Phoenix's medical crew.
- Weiss Reacts has Homura, Kyoko and Mami appear months before Homura Reacts was written.
- To Hell and Back (Arrowverse): There's a blink-and-you'll-miss-it mention of Talia al Ghul in the prologue.
- In Dairantou Saint Zearth, The Tenda Cousins appear on the first episode to sign the contract.
- New Beginnings (Smallville): Thanks to his future knowledge, Clark Kent meets Oliver Queen, opens the antechamber storing Jor-El's hologram and gets his cousin Kara out of her buried ship seven years earlier than in canon.
- Bethany Hawke is mentioned in passing five times in All This Sh*t is Twice as Weird before finally showing up in person to join the Inquisition in chapter 38.
- In Dragonball Divergence
, a much younger Videl appears in Chapter 8, during the transition between the Saiyan and Namek Arcs. She's visiting the hospital to bring her father food. - The Warrior's Daughter: In canon, Bulla is born at Age 780 and shows up in the epilogue of the original series. Here, she is born at Age 766 and shows up in the beginning of the Android Arc.
- Fate/Gamers Only: Kagetora makes a background appearance in the first GUDAGUDA event, when she'd made her first in-game appearance with the fourth GUDAGUDA event.
- In Game Theory, several characters from later seasons, such as Zest, Quint, Megane, and Tiida take part the Jewel Seed incident. Teana also gets a brief cameo, and although the girl in a wheelchair is never actually named, it's pretty clear that she's Hayate.
- Gil Graham is initially mentioned in passing and eventually appears himself along with the Liese twins. (In fact Lotte Liese is an 11th-Hour Ranger.) Quint also holds a conversation with her husband Genya (another example of this trope) where they talk about the two girls they're trying to adopt - clearly Subaru and Ginga. And finally Lutecia appears as a baby.
- The sequel, Power Games shocked everyone when the Mariage popped up during the Book of Darkness incident. Amazingly the author had subtly foreshadowed it in advance. Shortly afterwards, Jail and some of the Numbers enter the story.
- In Juxtapose, the Wild Wild Pussycats show up much earlier to set up the Sky Garden for the Sports Festival with Kamui Woods. Hawks appears at the same time as a spectator.
My Little Pony: Friendship Is Magic
- In The Elements of Friendship, Shining Armor appears briefly in Bonds. He isn't mentioned by name and has a brief, awkward conversation with Twilight, hinting that they're estranged.
- The Flash Sentry Chronicles: Towards the end of "Into the Forest" a mysterious female shirks the Scorpentine that stung Scootaloo and claims she has plans for it. The figure is revealed to be Queen Chrysalis, when the same Scorpentine appears in the caves beneath Canterlot guarding Princess Cadance, Twilight and Flash.
- Junior Officers
- Lekona's wife Blythe makes two small cameos in "Kitsune Fox in Hat Trouble" and "Scary Stories to Tell in the Dead Sea" before making her official debut in "Blythe and the Risso's Dolphin".
- Sarabi was talked about in "The Undersea Twister" before being officially introduced in "New Squirrel in Town".
- This Bites!:
- Bartolomeo was present for Luffy's would-be execution in Loguetown in canon. In this fic, Cross takes the opportunity to temper his passion to be a pirate like Luffy, and suggest that he actually do it right (in canon, while he and presumably his crew had the necessary power to survive in the New World, they had very poor seafaring skills, making it an outright miracle that they made it as far as they did).
- Characters that would only appear in future locations, like the Whitebeard Pirates, the Marine higher-ups, or the Revolutionaries appear to show current events, or as spectators to Cross's SBS Broadcast, even though the Straw Hats have yet to meet them in person. As of Chapter 30, Admiral Akainu makes an appearance, and he does not like the SBS.
- Chapter 31 has both Doflamingo and Scratchman Apoo calling in to the SBS Broadcast.
- By Chapter 36, due to the popularity of the SBS, it's almost easier to list the characters who haven't made an appearance yet. Kaido being one large, glaring exception.
- Kinda justified since the manga only very recently showed anything about Wano, as Wano is shown as being utterly isolated. While Kaido and his lackeys do have access to Transponder Snails, it is rather doubtful that ordinary citizens do as well. And even if they did, even speaking against Kaido gets you kidnapped by his Mooks. He probably has outlawed listening to the SBS.
- Chapter 52 shows Charlotte Pudding listening to Lola's guest appearance on SBS. Despite all the change that the Straw Hats have brought about and the respect they have earned, she does not think much of them.
- Stussy makes an early appearance in the aftermath of Strong World, delivering Indigo to the World Government.
- During Omatsuri Island, we are shown Zou, and its rulers Lord Nekomamushi and Duke Inuarashi. More of them were seen in the Enies Lobby arc. They quite like Soundbite's Abbott and Costello, to the point decided to organize a baseball game as a substitute for their usual battles. Their aide Wanda swears revenge against Cross for that very reason.
- In Chapter 61, the Beast Pirates are finally seen for the first time pre-timeskip with their representatives Sheepshead and Ginrummy in Skelter Bite.note
- Hours 'Verse:
- In chapter 6 of Facing the Sun, a young Akira pulls a prank on Minato and Ryoji. He's later properly introduced in Intermezzo.
- The Other Side's Tatsuya appears in Butterfly Cascade to give Minato his original sword Misericorde, reforged into a dagger to pass onto Akira. He shows up again to give support to Minato after Philemon crashes his wedding and indicates that the Velvet siblings are getting too involved in human affairs, although that second appearance gets darkly subverted when it's revealed that it's actually Nyarlathotep in the guise of Tatsuya trying to manipulate him. Later, the series expands to include events from the Other Side timeline, featuring Tatsuya prominently in The Other 25th Hours and My Kingdom for My Heart.
- Kaori Furuya who has a major role in episode 47 of Pretty Cure Heavy Metal, appears as a member of Oriyama High's dance club with Hanae in episode 50 of Pretty Cure Perfume Preppy.
- Arc Corp: Amber, Jaune's youngest sister, is first mentioned in Chapter 18, as the person who'll succeed Jaune as director of the Vale office in the event of his death. She later appears (albeit unnamed) in Chapter 28 as the young girl complaining about being left behind on the Mountain Glenn mission, before formally joining the cast in Chapter 71 as an intern at the Containments Office.
- In Tales of Beach City (the 5th "episode" of the Connieswap series), Holly Blue Agate and the Amethysts from the Human Zoo make a cameo appearance on the painting in Critical Connie.
- Total Drama All-Stars Rewrite:
- Jasmine from Pahkitew Island appears in the second aftermath episode before the rest of the Pahkitew Island’s cast is introduced in the four parter.
- Also, Ridonculous Race competitors Sanders, MacArthur, and Brody appear in the four parter.
