Enthusiasm Versus Stoicism

Another sliding scale like Sliding Scale of Idealism Versus Cynicism. Where characters are plotted on this line depends on how emotive they are.

Is the hero calm and collected, or wild and Hot-Blooded? Does the villain lick blood from his knife with relish, or dispose of bodies stone faced?

Positions on this scale aren't static; characters shift with their moods but can still be placed by their baseline.

If he's not smiling, is he sad or is that his normal face? If he is smiling has something good happened, or is he just a happy person? Enthusiasm overlaps with discord, change or denial.

Stoicism parallels continuity, repression, and law. Everyone feels, so the criterion is how much they display the emotion. The brooder who'll betray the friends he secretly hates is stoic (however great his wrath). Manipulators are stoics because they're suppressing their genuine emotions to display fake ones.

Most manga and anime implicitly contain this scale as a theme because the characters must reach ever-greater emotional extremes to power-up but control their emotions to limit the area-of-destruction to enemies.

An Odd Couple or Red Oni, Blue Oni will occur when these two are specifically side-by-side.

Anime and Manga

 * Kazuhiko Shimamoto's works. His characters are Hot-Blooded, prone to suddenly bursting into tears, exploding into rage or cheering wildly and they Never. Stop. Sweating.
 * Moeyo Pen
 * Gyakkyou Nine
 * Anime Tenchou (which you may recognize from Lucky Star)
 * Blazing Transfer Student.
 * G Gundam'
 * Super Robot pilots
 * Mazinger Z: Kouji Kabuto
 * Great Mazinger: Tetsuya Tsurugi.
 * UFO Robo Grendizer: Duke Fleed.
 * Getter Robo: Ryoma Nagare.
 * Kotetsu Jeeg: Hiroshi Shiba.
 * Gaiking: Sanshiro Tsuwabuki.
 * Raideen: Akira Hibiki.
 * Combattler V: Hyoma Aoi.
 * Voltes V: Kenichi Go.
 * Daimos: Kazuya Ryuuzaki.
 * Zambot 3: Kappei Jin.
 * Daitarn 3: Banjo Haran.
 * G Gundam: Domon Kasshu
 * GaoGaiGar: Guy Shishioh
 * Tengen Toppa Gurren Lagann Simon
 * Great Teacher Onizuka: Onizuka-sensei.
 * Samurai Champloo

Comic Books

 * X-Men's Wolverine. Just try to find a picture where he's not screaming his lungs out while gleefully shredding something.
 * Easy, just look for any time he's paired with Jubilee. He'll go Blue Oni quick enough then.

Literature

 * The Brothers Karamazov: Most characters are bursting with feeling. Their conversations end up in hysterics.

Video Games

 * Final Fantasy VIII: Selphie Tilmitt is a Genki Girl with some bloodthirsty streaks. Zell Dincht is just really loud and doesn't stop moving.
 * Sonic the Hedgehog: Sonic when he gets worked up, Knuckles all the time.
 * Rouge, as an anti-hero-ish variation.
 * Mass Effect 2: Kasumi Goto.
 * Onion Knight, Tidus, Barts and Zidane (to the extreme) Prishe, Laguna Loire, Vann, and Tifa on the heroic side for Dissida.
 * Kuja, Jecht, and Kefka on the villainous side in Dissidia Final Fantasy

Webcomics

 * Octopus Pie: Hannah Thomspon is giddy, angry or something. There is no calm.

Anime and Manga

 * Gundam Wing has The Stoic Heero as its protagonist and Crouching Moron, Hidden Badass Duo as his Lancer. The show doesn't lean one way or the other in serious contexts, but more often than not Heero's cool head will allow him to flummox Duo for comedic effect.

Comic Books

 * X-Men's Cyclops. Renowned for his stiffness and abnormal self-control (paired with his ironically uncontrolled eye-beams he can't turn off).
 * While it might seem like his tight self-control is the result of dealign with being unable to control his destructive mutant ability, it was at one point revealed that his inability to control it was a subconscious decision he made as a child out of guilt for being unable to save his family (or even accidentally making the situation worse when their plane was crashing)

Film

 * There Will Be Blood: Plainview smolders with hatred for humanity he fights to contain. He leaves a town with oil reserves because the populace is too disorderly. He walks away from his son without a word when delivering him to a school for deaf people. Eli has to work him up to a yell in the Church of the Third revelation because Plainview's used to restraining his emotions and talking in conversational levels. Stoicism has clearly taken a hike by the end of the film.
 * Half Baked: The guy on the couch. Steven Wright has made a comedy career out of his unnaturally mellow stage persona.

Literature

 * Harald: One of the major traits of David D. Friedman's fantasy novel is that all of the major characters are stoic, especially the titular protagonist.

Video Games

 * Final Fantasy VIII: Squall Leonheart and this is a constant source of conflict throughout the game.
 * Shadow of the Colossus: Though  Dormin is mellow.
 * Shadow the Hedgehog. Unless he's angry, because then he becomes a raging psychopath.
 * Cloud, Squall (on par with his Final Fantasy VIII persona) and of course Lightning on the heroic side of Dissidia Final Fantasy.
 * Sephiroth, The Cloud of Darkness, and to an extent Golbez on the villainous side of Dissidia Final Fantasy

Web Original

 * Greg from The Wolf's Will is a far more composed person than his partner Tony Tony. Look at the start of this scene to see what I mean.
 * Sasha in Greek Ninja appears stoic, as oppose to the whole group surrounding her.

Western Animation

 * Raven from Teen Titans
 * Mandy from The Grim Adventures of Billy and Mandy so much so her not smiling is a law of reality. In the episode she smiles, physics breaks down.
 * Scruffy the janitor from Futurama.

Anime and Manga

 * Code Geass is exceptional; Lelouch hides his humanitarian motivation to be the villain he thinks people need.
 * Ai no Kusabi displays this theme with the social structure of Tanagura, but mainly the dynamic between Iason and Riki. Iason is the top ranking, stoic Blondie who is calm and rarely ever expresses emotion just like other Elites. Riki is the dark haired, bottom ranking, gangster of a mongrel that is defiant, wild and revered for it amongst other mongrels. Somehow, they are attracted to each other. As the story progresses, Riki becomes more subdued but reluctant to accept this change, while Iason becomes more emotive yet accepts how he's Not So Stoic anymore and it's consequences.

Film

 * The Dark Knight: The Joker wants to destroy peoples mind-numbing plans, the routines of job and duty, so they'll wildly grapple with the pointlessness of existence.
 * Coffee And Cigarettes: The opening sketch airs terminally lethargic Steven Wright with hyperactive Roberto Benigni—switching their characters.

Tabletop Games

 * Warhammer 40,000, where Chaos feeds off of emotion (the four main gods embody rage, desire, love and hope) and ruthless stoicism is the main alternative. Go too far on the scale and you get the Necrons, sentient robots who exist only to destroy life and serve the literal Grim Reaper (among others). Did we mention the Grim and Dark future is not a nice place?

Video Games

 * Oblivion: The Shivering Isles: Those blessed by Sheogorath with Dementia may emote but rely more on keeping their feelings secret, the better to surprise enemies with. Maniacs lose themselves in sensation..
 * Whenever Shadow tends to be paired up with any other character in the Sonic cast (Sonic and Rouge being good examples) he's usually the more serious of the pair. While Rouge invites him to go treasure hunting with her, he completely rejects the idea and wants to stay focused on the main mission. When he and Sonic team up briefly in Shadow the Hedgehog, he's annoyed at how much fun his blue counterpart is having.
 * In Dissidia Final Fantasy, this happens for both the villains and the heroes. Squall ends up with Zidane and Bartz, literally the two most optimistic characters on the side of Light. Hilarity ensues, of course.
 * Also, Cloud is the more quiet of his gang of four, which just happens to include Tidus, Cecil, and Firion. While Firion and Cecil aren't quite as enthusiastic, they certainly aren't as stoic as Cloud. Tidus, of course, is on the far side of the scale.
 * Funnily enough, Tidus winds up with both Cloud and Leon later on, and he is telling them a big story of himself...and the two are barely paying attention.
 * Lightning from Final Fantasy XIII has to put up with her ENTIRE team, composed of Tifa, Laguna, Vann and Yuna, who are all fairly optimistic and enthusiastic. She snaps at Laguna and Vann constantly for their optimism and carefree natures.
 * The only person on her team who actually matches her stoicism is Kain.
 * Also, Kefka usually is the crazier of whoever he happens to be alongside at the time. Most notably the Cloud of Darkness, who speaks in a calm undertone while Kefka can't help but laugh every second and act like a general nuisance.
 * Also, when Jecht is paired with The Emperor this can be seen clearly.
 * double for the one time Sephiroth has a conversation with Kefka, but Sephiroth arguably was just as enthusiastic as facing Cloud and Tifa. He just has a different way of showing it.