Adorably Precocious Child: Because of neither of his parents being around, he often has to handle matters by himself when out in the human world, though he still manages to retain his childlike spirit.
All of the Other Reindeer: Initially was a bully victim in school; fortunately school life gets better for him over time, even if it’s not perfect.
Cheerful Child: Not so much in the game, but here he's perky to boot.
The Cutie: Unlike in the game, he doesn't suffer a massive Break the Cutie moment, making his adorableness really shine.
Friend to All Living Things: Gets along well with the horrific monsters who live below his house, and loves animals. He even gives Widow a chance despite his fear of spiders.
The Runaway: In “72 Hour Weekend”, where the conflict is him traveling to New York City to look for his long-lost dad, as a couple of the monsters and his girlfriend pursue him.
Took a Level in Jerkass: Downplayed, but he's become a lot more grumpy and aloof in "72 Hour Weekend", as a result of being a teenager stressed out about high school and having to deal with an Insufferable Genius for a guardian.
Adaptational Intelligence: Exaggerated to hell and back and combined with Adaptational Personality Change, Gemini turned from an animalistic brute who aggressively chases after Isaac in the games to a highly intelligent self-appointed anthropologist.
Bookworm: He reads books and tends to be very knowledgeable about different subjects.
British Stuffiness: He is given a British accent for this AU, and is the most uptight among the Basement residents. Although...
Fake Brit: invoked Dark One accuses it of being fake during a heated argument, due to the fact that he’s not even from England.
Fatal Flaw: Pride. He's generally intelligent and competent, but his overconfidence about his abilities often rubs the others the wrong way.
Insufferable Genius: He can come across as a Jerkass and annoying to everyone around him as a result of his arrogance.
Intrigued by Humanity: Much of his character revolves around being fascinated by human culture, to the point where he even became an anthropologist.
Monstrous Humanoid: He can get away much more with exploring the outside world due to looking the most human out of everyone, just as long as Suture stays hidden.
Neat Freak: Unlike the other, he hates being dirty and bathes in water.
Only Known by Their Nickname: No one refers to him as “Contusion” except for Pride to an extent (who calls him "Connie") and Gurdy. Everyone else refers to him as "Gemini" because it's easier.
Parental Substitute: Plays the role of Isaac's father figure moreso than the other male monsters.
Reasonable Authority Figure: He's leader of the Basement, but is shown to be actually competent at his job and caring greatly about the other Basemenites, seeing them all as friends and family.
Took a Level in Jerkass: In "72 Hour Weekend", he's become a lot more arrogant and stricter with Isaac.
Trans Nature: He has an obsession with humans and often tries to emulate their mannerisms, while also having an aversion to the mannerisms of his fellow monsters.
Burning with Anger: When he gets angry, his eyes and forehead burn with purple fire.
The Eeyore: Tends to be introverted and pessimistic most of the time. Although he eventually undergoes Character Development and is now okay with hanging around the others.
Adaptational Ugliness: Believe it or not he’s one of the few characters who invert Adaptational Attractiveness. Not only is he lankier and has less stereotypically “cute” facial features than his original counterpart, but he also exhibits a grating, high-pitched voice complete with an Annoying Laugh.
Keet: When Loki’s not present, he usually takes up this role.
The Hyena: Laughs the most out of everyone else, mainly due to his tendencies to laugh at his own jokes. He’s also described having an Annoying Laugh.
Funetik Aksent: His dialogue is written like this, with his W's pronounced as V's and Th's as D's.
Funny Foreigner: He’s from Ancient Egypt, speaks in a thick Egyptian accent, and is quite eccentric. Although being from a completely different time period can account for that.
Kid Hero: He’s the youngest of the monsters, being 14 in monster years (15 in “72 Hour Weekend”), yet is the one who saves Eve from drowning when Dark One failed to do so.
The Prankster: Described as being the prankster of the group. At one point he stole Bloat’s eyes while he was asleep and locked them in a chest.
Age Lift: She’s a teenager by monster standards in the fanfiction and often acts the part, which, despite the age being unknown, is obviously not the case in the game.
Adaptational Attractiveness: Her actual design is a perpetually grimacing ghostly-looking mask, while here she basically looks like a white half-circle with a smiley-face.
Butt-Monkey: Often the butt of slapstick jokes and Bloat's bullying.
Dark and Troubled Past: Originally part of a freakshow during the Victorian times, before Dark One busted her out.
Suddenly Voiced: Around the end of "The Big Spill". Though she wasn't actually speaking, but rather using telepathy.
Hyperactive Metabolism: She can be in an extremely bad shape, yet still guaranteed to be fine if some form of energy enters her body, which includes food.
Mind over Matter: She has psychic powers, and naturally is telekinetic.
Psychic Nosebleed: She gets this whenever she uses her powers too much.
Bloat
Adaptational Attractiveness: “Attractive” is a big word, but his Body Horror is less obvious here. He looks less like a bloody, melting corpse and more like a chubby, grey humanoid with red streaks running down his body. His teeth are also more human-like and he lacks a cleft mouth.
Adaptational Wimp: Originally a boss infamous throughout The Binding of Isaac fandom for his killing of runs, now made into a petty bully who gets scared at a kid in a Halloween costume and punched out by a 13-year-old girl.
The Alcoholic: Has the tendency to get absolutely wasted the most out of everyone else.
Body Horror: Decay has affected his body quite negatively and he mentions having worms in his heart and his digestive tract having swelled to five times the normal size and covered in ulcers. He’s also implied to be bleeding from the inside constantly and mentions having severe scurvy. Though due to already being dead, all of these are simply minor inconveniences to him.
Butt-Monkey: Nothing ever goes right for the guy, ever.
Deadpan Snarker: Everything that comes out of his mouth is always some derisive comment.
Dirty Coward: He gets scared pretty easily, and is willing to abandon the others at any hint of danger.
Villainous Glutton: He has no limitations when it comes to his eating habits, and that includes cute animals much to the expense of Isaac.
Greed
Benevolent Boss: Surprisingly is this towards the other Sins with the exception of Pride (who’s a massive Jerkass which makes it understandable).
Daddy's Girl: A male example. He often threatens to call his father (Ultra Greed) when things don’t go his way.
Rich Bastard: Often invokes this stereotype. The richest guy in the basement and not afraid to show it. He also craves having more money befitting him being the sin of Greed.
What Kind of Lame Power Is Heart, Anyway?: He addresses his power of splitting into different heads as this, as he is envious of everyone else getting cool superpowers like firing lasers and shooting out fire.
