In media, there's a tendency for siblings to be portrayed as opposites. Enter the Foolish Sibling and the Responsible Sibling.
In this trope there will be one sibling who is foolish, usually acting melodramatically and prone to doing irresponsible and impulsive things. They may be louder, more outgoing and usually more popular (or at least try to be), and desiring attention, especially from the opposite sex. Usually, they don't have outright bad intentions, they just don't understand that anything they do can have consequences for themselves or other people. Alternatively, they may just be a Horrible Judge of Character and get involved with the wrong people on a regular basis; they refuse to believe their "friends" could be anything but pure of heart, despite obvious evidence to the contrary. Their antics will be their undoing, getting them into trouble for which there is no one but themselves to blame. The Foolish Sibling may be a Bratty Teenage Daughter, Alpha Bitch, Fille Fatale, Childish Older Sibling, Annoying Younger Sibling, The Casanova, Manchild, NEET, Dumbass Teenage Son, or The Ingenue.
The other sibling is usually the elder of the two (sometimes much older) and will follow all the rules about how one is supposed to act and behave, being an exemplary version of a Proper Lady or The Dutiful Son. They're often more of a parental figure in the other sibling's life, even if their actual parents are still present. They might be quieter or plainer, though usually they are only quiet or plain by comparison to their obnoxious other sibling, and doesn't qualify as a Shrinking Violet or The Quiet One at all. They're almost undoubtedly smarter though and may be portrayed as a Bookworm, or just very concerned about rules, social and moral. Generally, the responsible sibling will try to steer their foolish sibling to the right path, taking it on themselves to look after the kid and make attempts to curb the other sibling's behavior. This seldom works, however, at least not until the end, when the foolish sibling gets their comeuppance or realizes the error of their ways.
They may serve as a Betty and Veronica pair. The responsible sibling is the one who will submit to an Arranged Marriage, which may be a Perfectly Arranged Marriage and is generally happier than the foolish love match of the foolish sibling.
A Sub-Trope of Sibling Yin-Yang. Usually involves An Aesop about the right way to act, that is to say, be more like the responsible sibling and not the foolish sibling (although the responsible sibling may learn a lesson about "loosening up" and "having fun"). And while the responsible sibling is usually the elder of the two, the roles can be switched, with the younger sibling being the responsible one. Another possibility is a middle child being the responsible one to his or her older and younger siblings. However, there are some moments when the responsible sibling can act melodramatic and impulsive. Also compare Slobs Versus Snobs, Red Oni, Blue Oni, Right Way/Wrong Way Pair, All Work vs. All Play, The Glorious War of Sisterly Rivalry, and Cain and Abel.
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- Daredevil (Charles Soule) has responsible Sam and foolish Hannah. Sam works bad hours doing a crappy job in order to support the two while Hannah goes out clubbing.
- The main characters of Exorsisters, Kate and Cate Harrow. Cate is very mature and responsible, while Kate is a Hard-Drinking Party Girl. The twist is they actually aren't sisters, Kate is Cate's soul- Cate's mom made a Deal with the Devil and lost her own soul, but gave up Cate's to save herself. By the time Cate got her soul back, it was sufficiently different from her to become its own person, Kate.
- In Witchblade the main character Sara Pezzini is the responsible sibling to Julie Pezzini's foolish sibling. Sara is a cop while Julie has got into trouble, and has even gone to jail for dealings drugs.
- Wonder Woman Vol 1: Lila is the elder more snarky and much more responsible sibling to her sister Eve. The elder Brown sister has lost sleep trying to keep her sister's idiocy from getting her chucked in prison, and Eve was willing to sell government secrets to an Axis spy because she was embarrassed at the possibility he might publicly reveal she'd gone on a date with him.
- Classical Mythology: An Older Than Feudalism example is the Titan brothers Prometheus ("forethought") and Epimetheus ("afterthought"). While the former was clever and rational, the latter was foolish. In Plato's discussion of the myth, Epimetheus completely bolloxed everything when the two brothers were given the job of creating humans and animals. Since he lacked foresight, he came down to humanity last and had nothing more to offer, so Prometheus had to steal fire and give it to humans to prevent our extinction. According to Hesiod's Theogony, Epimetheus enthusiastically received Pandora from the gods, despite all of Prometheus's warnings that she would be a blight upon humanity. He was right, she was. This is the Ur-Example in Western Literature.
- Japanese Mythology: Foolish brothers are the reason why the Japanese pantheon is ruled by a goddess. Amaterasu's first brother, Tsukuyomi, killed the goddess of food out of disgust at the way she procured the food, so Amaterasu vowed never to speak to him again, hence why day and night are always apart. Amaterasu's other brother, Susanoo, was a Sore Loser who threw a massive tantrum after he lost a competition with her and was banished to Earth. His descendants initially ruled the world, until Amaterasu ordered her descendant to depose them.
- Rabbit Hole: Becca is the responsible wife and mother. Her sister Izzy is a wild child that gets into bar fights after having sex with another woman's boyfriendand gets knocked up by said other woman's boyfriend.
- DSBT InsaniT: Bill is the Foolish Sibling, and Whitney is the Responsible Sibling. Bill is bombastic and will charge right into confrontation. Whitney will try and approach confrontation nice and easy and will Take a Third Option if possible.
- In the GoAnimate "Character gets grounded" videos, a lot of the troublemakers have this dynamic with their siblings. It's worth pointing out that these are simply the most common dynamics between these characters in the grounded videos, and some videos have been known to reverse the characters' dynamics or even have both be Foolish:
- Ichabod and Calamity in No Evil, with Ichabod as the studious, neurotic one (Responsible) and Calamity as Brilliant, but Lazy (Foolish).
- Trick Moon: Prince is the responsible one, but as he is trapped he has to rely on his foolish siblings Trickshot and Pocket. Despite his obsession with looking "cool", Trickshot takes his job more seriously than Pocket, grabbing her when she stops to save her game after Mage steals the Moonstone.
- In Petscop: according to their descriptions, Roneth is the responsible to Toneth's foolish because he learns from the latter's mistakes and doesn't need to be watched all the time (implying Toneth does need to be watched all the time).
- Aaron has two brothers, Chris and Adam. Adam was a drunken wreck in his teen years, making him the Foolish sibling. Chris is well-adjusted and living away from home, making him the Responsible one.
- The Cry of Mann:
- Berry is the responsible sibling, to Jouglat and Jack's foolish sibling. While she works hard trying to keep the family from falling apart and tries to act as a moral compass of sorts, Jouglat goes crazy due to his warr obsession, and Jack spirals out of control due to his obsession with his art.
- While they're not actually blood-related, they're practically sisters, and they share this dynamic. Mabel's the responsible one, who tries to protect both herself and Ashes from the soldiers, whom she doesn't trust or care for. Even after she falls for Glintz-Terry, she refuses to take action and thinks of herself as being naive. Ashes is the foolish one, who chooses to flirt with soldier Durkin and shows no fear when dealing with the other soldiers, a mentality that Mabel chastises as being too foolish and dangerous.
- The Nostalgia Critic and The Other Guy. Also slightly played with, as The Other Guy is proud to reveal that he controls the Critic like a puppet-master. As they do a lot of videos as themselves reviewing modern movies, Doug and Rob will play this dynamic too. Doug's usually the ditzy, slightly crazy Wide-Eyed Idealist, while Rob is more cynical and can smack Doug down when he gets too far.
- In the "Bowser Junior's First Grade!" story arc, Emily Coleman, who is one of the few students who has some common sense and maturity, serves as the responsible sibling to her crazy brother, Patrick's foolish sibling.
- In "Chef Pee Pee's Family", Chef Pee Pee and his unnamed sister serve as the responsible siblings to their sister, Stacy's foolish sibling. In particular, Stacy spends most of her time cheering the same word: "Queef", much to their annoyance.
- In "The Koopalings! Part 2", Junior, Iggy, Roy, Larry, and Ludwig are the responsible siblings, while Wendy, Morton, and Lemmy are the foolish ones. In particular, Wendy smashed a dish over a spot she missed, and later cut the couch in half with a chainsaw which led to Mario and Bowser getting evicted from their apartment, Lemmy broke a table with a cannonball from Bowser's clown car, and Morton smashed another table with a hammer, with Junior trying to stop them all the while.
- Cream Heroes: Dodo is the Foolish, having jumped atop Claire's kitchen cabinets despite the dangers and has eaten soil, silicone and paper. This stands in contrast to his brother Toto, who tends to be calmer and more responsible, acting as a defender from the robot vacuum and the zombie hand massager. Notably, if Dodo doesn't go to DD or Nana for comfort when he's upset, he will seek out Toto.