A group of kids who get involved in the stories due to curiosity or other problems. Unfortunately, being a kid does not equal "safe" in these stories.
- Break the Cutie: in Through Darkness And Mirrors, the memory gap they suffer due to XANA's possession, as well as learning what that led to, Steven getting stuck in Limbo breaks them hard.
- Demonic Possession: All six of them suffer this in Through Darkness and Mirrors at the hands of XANA, who uses them to psychologically torment Steven Universe into falling into the Despair Event Horizon so that it will attract the darkness and give the Vex a sample to study, and after that, to shatter the Crystal Gems. Unlike most examples of Xanafication...they don't take it very well.
- The Fellowship Has Ended: They're still on good terms with each other, but they agree that they all need a break after Through Darkness and Mirrors has ended.
- Five-Man Band:
- The Leader: Dipper
- The Lancer: Mabel
- The Big Girl: Nanako (has fighting prowess and a Persona to boot)
- The Smart Guy: Jack (Dipper also qualifies, but Jack is the more inquisitive one)
- The Chick: Annie and Pacifica (Annie is known for her Friend to All Living Things mentality and pluckiness, whereas Pacifica tries to figure out her usefulness)
- Kid Detective: They form a group of this, but Dipper and Mabel qualify for this the most due to the types of adventures they face.
- Kid Hero: Ranging from age 7 (Nanako) to 13 (Dipper, Mabel and Pacifica), these kids are going to get involved no matter what.
Dipper and Mabel Pines (Gravity Falls)
Dubbed "The Mystery Twins", these two get involved for curiosity's sake in The Friendship Asylum and decide to help out after learning of Matt Hardy's trouble with his younger brother.
- An Axe to Grind: Mabel wields an axe in the final story.
- BrotherSister Team: They always have each other's back.
- The Cameo: They appear at the epilogue of Muse Hysteria and Mabel interacts with Sora in Diamond Adventure! The Dark Mystery
- Camera Fiend: Dipper in The Friendship Asylum who records his and Mabel's investigation in the dreaded mad house.
- Cute and Psycho: A heroic example with Mabel and her axe.
- Evil Laugh: Dipper does this in Through Darkness and Mirrors after stating "Present Day, Present Time!"
- The Knights Who Say "Squee!": Dipper jumps to the moon upon learning that Mystery Inc. is in the Pantheon.
- Nightmare Fetishist: Mabel absolutely loves Sora's Halloweentown outfit and a Running Gag is mentioned how much she wants an outfit just like that.
Jack and Annie (The Magic Treehouse)
Brother and sister team who uses their treehouse to fulfill missions from Morgan le Fay and Merlin, with magic artifacts that can only be used for good.
- BrotherSister Team: Just like the Pines above.
- Damsel in Distress: Annie gets captured by Decade (transformed into Xaldin) to be used for a Princess Test in Muse Hysteria.
- Foil: To the Pines. Whereas Dipper and Mabel are more into supernatural threats and can kick ass, Jack and Annie are more into history, fantasy and use their magic in non-violent ways. Not to mention that Dipper and Mabel are twins, while Jack and Annie are one year apart.
- Hour of Power: Their vials of the Morning Mists of Avalon; they wish to be whatever they want and will gain the skills/strengths/abilities of said whatever for an entire hour. They're used in the last story to let the Mystery Kids be wrestlers.
- Imagination-Based Superpower: The Water of Imagination. Just one sip of this, combined with whatever they imagine, can make anything they wish for become real.
- Lethal Joke Character: They may be kids who use their treehouse for learning and undergoing missions, but they're apprentices to Morgan le Fay and Merlin with artifacts that are just as powerful as the wizards.
- Magic Wand: The Wand of Dianthus, made from a unicorn horn of the legendary unicorn of the same name. To ensure that it can't end the story right there and then, it has 3 rules: It can only be used after Jack and Annie have done their best, it can only be used for good, and whatever they wish for must be EXACTLY five words, no more, no less. Nanako uses it as a makeshift weapon to pierce Jeff Hardy's eye out and then use its magic to help gather enough energy to Elena so she can heal Gentaro and the CMC in the final story.
- Must Make Amends: Upon learning the chaos they caused (see below), the two have decided to team up and stop the madness in the final story.
- Nice Job Breaking It, Hero!: While they did stop the Darkness Proxy from unleashing more chaos in Muse Hysteria, hurling them back into the asylum turned out to be a bad call. Because the Keystone of Limbo was in Yugi's soul—originally Alt!Gentaro but that's another story—the asylum became sentient upon feeling the magics within said Keystone, causing it to kickstart the corruption spree in The Friendship Asylum. Voltaire was right to question them as to why they didn't just purify the Proxy then and there.
- Oh, Crap!: The looks on their faces after they realize the trope above.
- Plucky Girl: Annie's shown to be able to bounce back from any and all situations well, not all but still.
- Spanner in the Works: Alt!Gentaro saw nothing of importance in Jack. Bad choice since Jack and Annie using the Wand of Dianthus blows him and the Darkness Proxy back to the asylum at the end of Muse Hysteria.
- Too Awesome to Use: The Wand of Dianthus can be used for anything the kids want, but it follows the rules of its universe, thus the two can only use it in desperate situations and have a five word limit.
Pacifica Northwest (Gravity Falls)
Daughter of the richest family in Gravity Falls, who only gets sucked into it after being asked by the Pine Twins. Despite her sarcasm, she feels like she can't contribute anything to the group.
- Deadpan Snarker: Sarcastic about almost everything; it's usually her way of coping.
- Desperately Looking for a Purpose in Life: States that she's trying to figure out what to do now after the Weirdmaggedon situation in her own series.
- The Drag-Along: Only got roped into this because Mabel begged her to join.
- Improbable Weapon User: She wields a golf club when it comes to fighting.
- Mythology Gag: She's good a mini-golf, as seen in her show.
- Sour Outside, Sad Inside: Laments her uselessness since she honestly has no idea how to fight back.
- Wrestler in All of Us: After using some of Jack and Annie's Morning Mists of Avalon, she decides to tear down zombies with wrestling moves, one of them being the Burning Hammer.
Nanako Dojima (Persona 4)
The cousin of Yu Naraukami, she got involved after she saw her friends dragged into Limbo and teamed with the Mystery Kids in that regard. Unlike the other Mystery Kids, she has a special power...a Persona.
- Ascended Extra: Originally appeared in one of the Pantheon Tales (Shattered Illusion which is confirmed as a prequel to Through Darkness and Mirrors) and becomes a major factor in the final story.
- Badass Adorable: A pink belly-dancer who wields a scimitar, can summon a Persona is a skilled crackshot who shoots a zombie about to hurt her dad and stabs a Darkness-possessed Jeff Hardy in the eye. Don't mess with this chick.
- Cute Bruiser: Looking at her, you wouldn't expect this sweetie to use a gun, behead zombies, pierce eyes out, or set people on fire.
- Bedlah Babe: A PG-version of this. This is her Decemberween costume.
- Berserk Button: Do not hurt her father or she will shoot you.
- Beware the Nice Ones: The sweetest girl you'll ever find, and the goddess of Everyone's Baby Sister...then she reveals that she has a Persona and can and will shoot you, slice your head off and pierce your eye out to survive.
- Combat Pragmatist: Like you wouldn't believe. When Jeff Hardy is close to choking her, she grabs Jack and Annie's Wand of Dianthus to pierce his eye out before commanding Throne to incinerate him. And she beheads a zombie prior to that.
- Dance Battler: She usually twirls and spins like she dances. Word of God is that she trained with Shantae in that regard.
- Dark Is Not Evil: Her Throne Persona is a grey-skeletal figure wearing a black cloak and has five arms that hold onto a flaming wheel...but Throne is an angel who is the closest to God's spiritual perfection and a judge that can deliver punishments without bias, and is used by the sweetest and cutest girl ever.
- Unfortunately, XANA's possession of her brings this into Dark Is Evil territory.
- Foil: She's one to Mokuba; both of them are Quasideities and the youngest members of their groups who look like they shouldn't be involved in this madnesss. They both showcase Big Brother Worship (in fact, Nanako used to be in the same House Mokuba currently is right now) and have an overprotective older brother (Yu for Nanako, who is The Ghost in the story and Seto for Mokuba who unintentionally wreaked havoc in the trilogy). The only difference is how they get involved in the fighting and how they react to everything that goes on.
- Heroes Prefer Swords: Her weapon is a (toy) scimitar later upgraded to a real one after sipping a vial of the Water of Imagination.
- Sinister Scimitar: Again, she's using a scimitar as a weapon.
- Little Miss Badass: She's The Big Guy of the group (at the age of 7) who uses a scimitar, a fire-casting Persona and a gun to get rid of any and all competition.
- Mythology Gag:
- She spins and dances when she fights; Persona 4 Dancing All Night reveals that she's able to learn complicated dance moves pretty easily.
- She's shown to be interested in Dipper and Mabel's detective work; she's seen helping Naoto in her Social Link and she's into a magical girl detective series in the anime.
- Her wielding a gun isn't new; in the game, Dojima mentions bringing her to a shooting range under a pretense that it was a game. According to him, she's pretty skilled at it.
- Off with His Head!: Decapitates the head of Mirror!Kaiba with her scimitar but not before shooting him multiple times and incinerating him.
- Pink Is Feminine: Her Decemberween outfit is her dressed as a pink belly dancer.
- Playing with Fire: Throne's capable of unleashing Agidyne when the situation calls for it.
- Kill It with Fire: And Nanako's not afraid of committing arson, btw.
- Pre Ass Kicking One Liner:
Nanako: "Hey, heads up!"
- What she says to Mirror!Kaiba before decapitating him.
Jeff: Don't try and stop me, little girl. I'm doing this all in the name of justice!Nanako: Oh yeah? Well, I heard that justice is blind! (pierces Jeff's eye out with the Wand of Dianthus)
- And here's what she says when Darkness possessed Jeff Hardy tries to kill her.
- Sword and Gun: During the Zombie Apocalypse in the last story, she wields a flaming scimitar and her father's gun before she goes to town on the undead.