Alternative Character Interpretation: Axis Powers Hetalia
Since the cast of Axis Powers Hetalia are nations and the series itself is mostly light comedy, this is to be expected. A few strips hint at much darker humor or hidden angst; fandom often takes the idea of history-as-canon and carries it to the logical conclusion. This makes for potentially VERY dark characterizations for most countries, especially those with imperialist or colonialist eras.
There are two general lines of interpretation for Canada in the fandom: "moe" Canada that emphasizes his sweet, timid, and unassertive demeanor (sometimes to Woobie levels); and "manly" Canada, mostly by people who don't like the way he's portrayed in canon, that plays up his assumed passive-aggressive tendencies (sometimes to the point of making him an unabashed Deadpan Snarker) and gives him an overall Darker and Edgier characterization. This is sometimes flanderized up to the point where he's an Ax Crazy psycho who goes around raping everybody.
A lot of fan authors and fanartists depict a very close, loving, brotherly relationship between Canada and America, even though the manga describes America as "the root of Canada's unhappiness" and it's shown that Canada, while not outright hating him, resents his brother a lot. So much that his Crowning Moment of Awesome consists into almost talking America to death. On the other hand, some fans posit that all this is just typical sibling behavior and that just because Canada likes cutting America down to size occasionally, it doesn't mean that he doesn't genuinely love and care for his brother when the chips are down (as evidenced by him consulting America for advice at least once in canon).
Russia is the one who gets the most varying interpretations. Is he a Complete Monster who only wants to torment others, or a Woobie who's become so emotionally damaged that he can't think rationally anymore? Could he be accurately called a Manipulative Bastard who knows how to press his victims' buttons, or is he too childish to be capable of such conscious manipulation or even be fully aware of the morality of his actions? Does he want to become one with everybody so that he can destroy them, or ensure that he can never be hurt anymore, or simply to cure his loneliness or pain in the only way his warped mind can comprehend? And does he truly love Lithuania (probably a little too much), or is Lithuania just a convenient target for him to vent his anger and frustrations upon?
Many fans portray China as being secretly wise, with the reasoning that he's the oldest of the nations (although Really 700 Years Old and Immortal Immaturity are in full effect in this series), and general depictions of his character seem to be split between "long-suffering nation who's been kicked around for a long time and thus doesn't have much in the way of aggressiveness" and "nation who won't let others kick him around anymore and thus acts jerkish toward them." If his real-life history is brought in, he becomes either a Broken Bird who's been hurt over and over again by the betrayals of his siblings or a Broken Hero who's gone through a lot of grief and hurt but nonetheless has overcome them and can still smile and be happy.
And then there's his relationship with Japan. Is China's obvious affection for Japan purely familial or more than that, and in either case, does Japan simply not return China's affections or does he actually reciprocate them (familial or otherwise) and is just reluctant to admit it? And while we're on the subject of relationships, just what does China think of Russia, especially after the Cold War/Sino-Soviet split?
Also, we cannot forget his relationship with Hong Kong and Taiwan. A well-meaning Team Mom who nags his younger siblings and unadvertingly pushes them away while trying to help them, or a dangerous Yandere who would rape them into submission if he could?
Taiwan and Hong Kong themselves are subjected to this too. Is HK a real Emotionless Boy whose psychological development was stunted while growing up with England, a Sugar and Ice Personality who cares deeply for China and the others and just Cannot Spit It Out due to his mixed raising, or just an Comically Seriousprankster who deals with said baggages by playing tricks on everyone and just doing what he wants now that he can do it? Taiwan: was she married/engaged to Japan in the past (more exactly, during the time she was his colony), is her liking of Japan mostly based on rebelliousness towards China than real feelings for him, is she a victim of Stockholm Syndrome after her times with Japan, or is she Yanderetowards him - like Belarus is towards Russia (only more subtly)?
There's also the characterization of him as a Stepford Smiler who puts on a Jerkass Façade to hide his loneliness and fears about disappearing/being forgotten in dramatic works.
Let's not forget Norway! Are his feelings for Iceland purelybrotherly or beyond that? Does he hate Denmark after the end of the Kalmar Union, which fanon seems to see as them being "married"? Is he a Tsundere towards Denmark (and just how much of a Tsundere is he?), or is he a potential Yandere who covers his obsession with his Deadpan Snarker tendencies? And what does he think of Sweden after theirunion in the 19th century?
W-wait, we've gotten this far without even mentioning Germany? Or is that just way too obvious?
There's the recent trend of making Spain a Yandere or Cute and Psycho, due to the extremely complex history that the country has gone through. Apparently, no one can be that much of a Nice Guy in Real Life...
Himaruya has supposedly confirmed that Spain's a Yandere, but most fans disregard this since it's never been shown in canon.
No, Himaruya hasn't actually confirmed that Spain is a yandere. He did use to have some notes on his site about how Spain was two-faced and his treatment of his other colonies was the flip side of his treatment of Romano, but these notes are extremely old and were taken down a long time ago so they're probably not accurate right now, and while Spain did seem to have a "dark" moment during the 2011 April Fools event, it was mainly Played for Laughs and no further mention was made of it.
Is Japan merely The Stoic with no other noteworthy traits, or is he more complexthan that? If the latter, then does his stoic exterior conceal a genuinely sweet but socially awkward person or mask a muchdarkerpersonality? You can actually predict which interpretation fans support by looking at who they ship him with: if they ship him with Greece, he'll almost always be the former, whereas if they ship him with China, he'll almost always be the latter. Other pairings for him tend to be more evenly split into these same two categories, depending on whether the fic is history-heavy or not.
About his rival Turkey: Jerk with a Heart of Gold who has a soft spot for Japan and actually cares for Greece deep down? Loveable Sex Maniac who hits on anyone he thinks would make a good harem member? Jerkass who gets his kicks out of provoking any kind of reaction from his longtime rival/BST partner? Manipulative Bastard who'd rape Greece just to put him in his place and make him kowtow to him? And did he rape Hungary or not right before/after the fight that was followed by her and Prussia more or less realizing her real gender?
Italy Romano: A misunderstood grouch with simply a huge inferiority complex stemming from his grandfather ignoring him and feeling that Spain and others want to use him for his inheritance, a useless whiny manchild who was too spoiled of a brat that still deserves to be spanked, or a grade-A Jerkass that simply likes being an annoyance to everyone? Then there's the matter of if he has "deeper" feelings for Spain but acts like a jerk to throw him off, or if he actually hates Spain and is just stringing him along in hopes to manipulate him as payback.
Let's add Korea to the list of APH characters who get Darker and Edgier characterizations in Dark Fic, shall we? It's especially noticeable with him as his normal characterization is as an unfailingly cheerful if somewhatoverbearing guy with a hilariously overzealous affection for China, and the typical "serious" characterization of him essentially filters these qualities through a dark looking glass, reinterpreting his intense devotion to China as a hint to how his cheerful and childlike demeanor conceals an emotionally disturbedor stunted individual. There's even a semi-popular fanon theory that Korea actually represents both Koreas and suffers from multiple personality disorder with "North Korea" arising from his bottled-up negative emotions, even though it's been confirmed that South Korea and North Korea are separate characters.
Then there's Poland. Ditzy airhead with an affinity for wearing skirts and playing with pink ponies? Or a Phoenix-like character who always stands his ground and refuses to give up no matter who tries to beat him down? Or both? There's no rule that says he can't be a PluckyDeterminator who just happens to really like wearing skirts and playing with pink ponies, after all.
Lately, the canon strips seem to go for making France a mix of these things, thus making a Casanova Wannabe who does hit on everyone and snarks at some, but is quite capable of showing Hidden Depths (and a surprisingly good understanding of human nature) when the chance calls for it. When he meets with Lisa, the girl who might be Joan's reincarnation he only flirts with her a little, but acts much more like a Big Brother Mentor; similarly, he's rather kind to the French military man who recognizes him as a supernatural entity.
There's also Sweden. Is he totally as the comics seem to (and fandom loves to) portray him as? A misunderstood and much kinder on the inside guy than what his thug-like face says? On the other hand, if he exudes such a constantly threatening aura that's likely worse than even Russia's, where does that come from? Was he really a doting 'husband' to Finland or was he controlling and possessive? (He does get rather grouchy at the implication that Finland might have been happier with Russia). Is he uncomfortable with how scary he looks, or does he willingly intimidate others? And who let this terrifying man buy a child off the internet, anyway?
Is Finland still "living" with Sweden because he genuinely cares for him? Is he next to Su-san's side just because of Stockholm Syndrome? Or hell, can it beboth in the end? Sweden himself seems to be quite enamoured with Finland, but Finland's side of the story is not that clear if you think about it.
There are also at least a few fics who take advantage of the Kathoey/Ladyboy culture in Thailand to make him into a sassy Wholesome Crossdresser or Drag Queen in his spare time.
How about Romania? Is he an actual vampireand a nation? And what about his relationship with Hungary: Is the Belligerent Sexual Tension between them really about Transylvania (Truth in Television, Transylvania was exchanged between Hungary and Romania A LOT through the years), or is he just a Type B Tsundere towards her, hiding that Romantic side he is said to have in favour of annoying her? In several artworks, people depict him more as Cute and Psycho or Yangire, complete with Fangs Are Evil and a Slasher Smile.
Some people have characterised him as being almost at ADHD levels or the mind of a young child, even though he seems rather tame in his canon appearences, with a few strange moments (wanna history lesson on Vlad the Impaler, anyone?).
Vietnam's personality in fanworks comes in three general flavors: 1) A serious and mature Lady of War and Team Mom with a Sugar and Ice Personality, 2) a Broken Bird with a possible Split Personality from her civil wars, and 3) a Tsundere who's fond of using her rice paddle as a weapon against people who annoy her (mainly America, China or Thailand).
"Snapped!(character)" characterisations are fairly popular; this refers to the characterisation of whichever character as a Yangire.