Alternative Character Interpretation: Because the characters are countries, and no country has a clean past, it's not very hard to find muchdarker interpretations of the characters, especially when set during the past for any colonial power. In fact, the series has its own page for the trope.
There are even fans who take offense to a Visible Minority of the Japanese fandom turning him into a Possession Sue and cite this as a reason to not like him, forgetting that not only is that an absurd reason to hate the character himself (is it the character Japan's fault that his fandom likes warping his canon personality?) but that the Western fandom, or rather, American and Canadian fans do the exact same thing to America and Canada.
Additionally, compare the popularity of any Japan pairing in Japanese fandom to its popularity in Western fandom. Of all Japan pairings, only Greece/Japan comes anywhere close to matching its popularity in Japanese fandom (and it's mainly because its popularity in Japanese fandom is relatively modest compared to other pairings like England/Japan and America/Japan) and pairings like Turkey/Japan and Netherlands/Japan are virtually nonexistent in Western fandom in spite of having decent-sized fanbases in Japanese fandom.
Einsamkeit, Germany's theme. Whereas most character themes are fast and heavy this one is soft and mellow- (For Germany, of all nations!) and it works.
There's also Germany's Anthem. Eins, zwei, drei , vier, fünf!
Also joining the ranks is China's 2nd character song, 'Aiyaa 4000 Years'. Made even more liable to make one cry when one realizes it's got a large focus on Japan's betrayal and harm of China - even though it was taken out of the anime.
The character single of Belarus and Ukraine, Carrots and Sticks. Just the beginning of it sounds awesome and sounds like a certain Russian band. Now that the song has come out, it has become very popular.
At the same time, Iceland's Character Single (With Love from Iceland) is just as popular. Must be his voice, as well as Mr. Puffin's appearance.
Base Breaker: ALL countries when it boils down to it, and certainly those whoever had an Empire, will have a morally questionable history in somebody's mind.
There's strong division over whether England should be the seme or uke. As custom for slash fics and art, many fans will exaggerate England's more submissive and feminine traits. But then you have fans giving him the badass seme treatment, often to Ron the Death Eater levels, because he was an empire and therefore must always top.
Russia is a...unique character, to say the least. He is portrayed as much more flawed than the other characters, especially in earlier strips. Therefore, fans' viewpoints on him tend to be polarizing. And let's not get started on his many fanon portrayals...
Broken Base: Oh boy, where to start? Funimation's release of the English dub has taken the previously more-or-less united fanbase (outside of Shipping) and shattered it, probably beyond repair. Within hours of Funi showing some rather controversial scenes at a convention, massive flame wars erupted over the script changes and both fans and the haters of the series have gone neck to neck in attacking each other, if fans at each others' throats were not enough. Fans of the dub call it a perfectly-localized version with freshly-researched new lines, while those who hate it call it a cheap, bowdlerizedSouth ParkFollow the Leader that goes completely against Himaruya's own views and enters tasteless territory. The flames have yet to die down.
To a lesser, more amusing degree, the new Volume Five character designs. Himaruya seems to have done an art upgrade on Romano, Hungary (whose chest is now strangely flat in the cover, though is normal in the inside pages), Austria and Spain. Hetalia LJrs are conflicted as to whether the changes are good/bad. YMMV.
The Nyotalias, too. While most fans enjoy it, others seem to think of it as needless Fanservice. Also, many people have been complaining about fangirls taking the female version of the personification of their own nation/their favourite character and making them into Possession Sues.
Fem!Prussia in particular seems to have received a lot of hate for being inaccurate, mainly thanks to things as being an Action Girl wearing a miniskirt.
The female characters in general tend to break the base. Do they have any potential to be as interesting as the male nations, are they just useless filler and dragging the story down, and is Himaruya a misogynist for not making more of them or making them "lesser" countries? Tread very carefully in these discussions. Sometimes this feud can also extend between fans of the canon female nations vs. those who prefer the Nyotalia ones.
Crazy Awesome: Prussia. His ego could choke a horse, he's a boundlessly ambitious psychotic punk who delights in mischief, and yet caves at the sight of cute things... a freak among freaks, and a fan favorite. Plus, he, Spain and France together form a posse often dubbed the 'Bad Touch Trio', 'The Badass Trio', or 'The Bad Friends Trio.' They're just a trio of Badness.
Crosses the Line Twice: Some of the lines of the Funimation dub are this. Romano especially seems to receive the brunt of them.
Dry Docking: More than one fan has admitted to shipping England with other characters so that they can have America all to themselves. Or wanting to be the one to make Russia feel better. Or pretending that Greece and/or Turkey aren't interested in Japan. Or...seriously, you can find at least one fan that has this attitude with any nation; you can even find [Insert Nation here]/Reader fics if you know where to look.
For the lazy and curious, all you have to do is hit up DeviantArt. Nation/Reader fics are quite popular there.
"Marukaite Chikyuu, marukaite Chikyuu, marukaite Chikyuu, boku Italia~"
And since France's character CD was released: Para pappara parii pappari pari papparero!
What about Russia's Pepepe pepepepe pechka. It makes him sound absolutely adorable. "Pechka" apparently means "stove" in Russian, albeit it's not a stove like to cook something with, it's more like a fireplace. Which makes sense considering the first part of the song is about how "swan lake has frozen over" and that it's cold, and that he hates being cold.
Ensemble Darkhorse: Prussia, Hungary and Belarus are probably the biggest examples, though with such a huge cast every character is bound to have some sort of a following. And the other Nations may have trouble remembering who Canada is, but the fans sure don't.
As a whole, the Nordics is one of the more popular groups. Character wise, Denmark was the most popular until the 2010 Bloodbath where Iceland became the most popular within those few days due toobvious reasons.
Take in account this for example: Denmark was an Ensemble Darkhorsebefore appearing in any strip.
It seems that even the most minor of characters can become something like this-Lately, a character who appears in two episodes without even a canon name, has gotten attention just for looking exactly like England and America's lovechild. The fandom has named him Allen Kirkland-Jones, and he already has a fanclub-see for yourself.
Canada, especially considering how few strips he's appeared in.
From the Gender Flip versions Fem!England is the most popular of the girls and Male!Belarus seems to be the most popular out of male genderbends judging by the amount of fanart on Pixiv.
And if all of the above hasn't given it away, it's pretty clear that Himaruya is very much aware of how popular and loved they are.
And no love for Poland?
Aside from the main 8 and the Nordics, the Asians seem to be the most popular group. Well, with characters like Korea, Hong Kong, Taiwan, Thailand and Vietnam, it's not hard to see why.
Fan Nickname: South Italy is almost always just called Romano by the fandom and the author himself, to avoid confusion with [North] Italy (his name, Veneziano, does not show up nearly as often).
At the insistence of early fans, Himaruya supplied many characters with alternate human names. These continue to be used throughout the fandom, such as in Alternate Universe fanfics were the characters are not countries, or as personal names which are used alongside their nation names. Many characters who were not given a human name by Himaruya have a main fanon alternative.
Due to his character design, Germania is sometimes called "Legolas".
Many Japanese fans refer to England as "Iggy", a shortened version of "Igirisu" (= the UK in Japanese). The English language fandom took this a step further and uses "Iggy" as other characters' nickname for England in fanfics. Although the author has also used "Iggy" in the manga, there's even a strip about England titled "Iggy-Iggy Annoyance".
The Taiwanese side of the fandom calls its nation-tan "Wanwan". Others try to bypass Taiwan's lack of "human name" and call her "Meimei", which means "little sister" in Mandarin Chinese, or simply "Mei", which means "plum blossom".
Poland calls Lithuania "Liet", which has been adopted by the fandom. It comes from Lietuvos, the endonym for Lithuania.
On the non-humanoid side, the bird sometimes found on Prussia's head has been dubbed Gilbird.
Fanon: What many fans assume to be true about the series and its characterizations is more often this. Which can be justified in a way, given the material and canon itself. After all, you have history to back it up.
Bulgaria - doubles as O.C. Stand-in. His appearances (both manga and anime) are so short that fanworkers are at odds with any kind of characterisation. His most popular "personality" is a Jerkass with a Hair-Trigger Temper. This has actually been Jossed after Hetaween 2011 and the 2011 Bloodbath, where he's depicted as a soft-spoken Nice Guy.
Ukraine (like Canada) is sometimes depicted as a Silk Hiding Steel due to her country's history with the Cossacks. She is also being hinted as being a Yandere, as a result of her character song.
Fandom Berserk Button: Do not call France a "rapist", Spain a "pedophile", Russia a "psychopath/murderer", or other characters similar names.
A bit more understandable when one considers the fact that they were both web-based creations that became immensely popular incredibly quickly at around the same time; overwhelming amounts of fanworks for both began around 2009, and the people who'd begin butting heads were therewith.
Lately this has also become the case with Polandball, because of similar premises, and both fandoms accuse each other of being either insensitive or historically inaccurate. Unlike Hetalia, Polandball was not created by a single author. Also unlike in the case with Homestuck, this rivalry seems to be not cooling down any time soon.
Fan-Preferred Couple: It's safe to say that every single combination of two (or more) nations, no matter how cracky or canon-dubious, has someone out there shipping it. That said, there are some non-official (though in most cases, buoyed by Ship Tease) pairings that are preferred by the majority of fans: America/England, Spain/Romano, Poland/Lithuania, Germany/Italy, and Sweden/Finland.
The FPCs also tend to vary depending on the fandom/country: England/Japan is the runaway FPC in Japanese fandom and Russia/China is hugely popular in the Russian and Chinese fandom, for example.
Additionally, incest pairings tend to do well in Japan, which explains why Germany/Prussia, America/Canada, Romano/Veneziano, and Norway/Iceland tend to garner bigger followings there (ESPECIALLY Germancest; it's way, way more popular there than the semi-canon Germany/Italy).
Faux Symbolism: Cyprus's asymmetrical hair make it look like it's been cut in half, his one side making his head look like Greece's and the other more like Turkey's.
Or the fact there is the Karpas Peninsula in Cyprus. Which kinda resembles the long hair strand.
Foe Yay: In Fanon, Hungary with Romania, emphasis on the 'foe' part, because they hate each other with a burning passion. They probably have one of the strongest cases of antagonism. And this is true in Real Life, too, as Romanians and Hungarians have somewhat settled down in these regards but still, very understandably, have some serious differences to settle. Doesn't stop fans from making Romania her Third-Option Love Interest, after Austria and Prussia.
Hilarious in Hindsight: In Spain's version of Marukaite Chikyuu, you can hear Soccer/Football sounds, such as a ball being kicked and a referee's whistle being blown. Guess which national team won the 2010 FIFA World Cup?
The series in general can experience this, and in the Japanese side of fandom on 2ch, fans have been known to come to blows over Himaruya himself and his habit of not finishing things.
It's Popular, Now It Sucks: Some fans of the webcomic are not so thrilled about the surprising success of the anime and the influx of new fans. The funny thing is that most of them only started complaining when the fandom was already huge.
Jerkass Woobie: Russia and Prussia. They've pulled massive crap on others, but have had extremely sympathetic moments as well.
Belarus became this when Russia threatened to send her to Siberia because Lithuania expressed reservations about accompanying him to a meeting. Can you imagine your own brother caring so little about you that he uses sending you to the horror that was the gulags as an incentive to make someone else do what he wants? If this happens on a regular basis, her bitterness comes as no surprise. Even if it's Belarus, that's just not right.
Oh Italy. It doesn't matter how useless everyone thinks he is, there are still quite a few countries in this show that want to occupy his vital regions. As for the fanbase, the fans seem to have a tendency to convert their homelands into little black dresses. America and Japan get around a lot. England, too, mostly because he's a very popular character.
Even the fanbase seems to think that everyone will be one with Russia...
Japan. How many nations is he paired up with in Fanon? Especially by Japanese fans? Even in the English-speaking fandom where he gets much less shipping attention than the Western countries do, it's probably telling that it can be hard at times to tell which ship is the most popular one for him with Japan/China, Japan/England, and Japan/Greece being within spitting distance of each other popularity-wise and several other Japan pairings having smaller but just as loyal followings.
England. He's one of the most popular characters in both the Japanese and English-speaking fandoms. He gets around. A lot. As evidence, his facebook fanlisting has the largest amount of fans out of any country in the series (over 10,000 fans and counting). He also came 2nd in a character popularity poll hosted on the official Japanese site of Hetalia's publisher Gentosha, losing out (perhaps inevitably) to Japan - here. And he actually came in 1st on an earlier character popularity poll, beating out even Japan.
LGBT Fanbase: Turkey has a uniquely bara-like appearance that makes him adored like woah among the gay/bisexual male fans, or at least the Japanese ones. On Pixiv, more R-18 pictures have been produced of him than France!
On the Les Yay side of the fandom, lesbian/bi/pan female fans tend to be quite fond of Hungary, Ukraine and Belgium.
Memetic Badass / Memetic Molester: Although it's his unrepentant badassness that makes him so popular, his fandom's memes are even scarier: 'Prussia will occupy/seize your vital regions' and 'Prussia is 5 METERS LONG!'. In fact, Prussia is said to run around 4chan trying to seize the vital regions of the various boards. He even took over the main site for an April Fool's event. It may be rubbing off onto the actual anime, he acts very scarily in the below strip in the anime.
Mexicans Love Speedy Gonzales: Some fans like the character representing their nation more, because whenever he appears they can get all the culture references before they are explained (or even when they are not explained at all).
America is Number 2 favorite character in a poll on the American side, whereas in the Japanese poll his position can range anywhere from 4th to 9th. Americans like making fun of themselves?
Even Americans who hate Hetalia often receive him well.
South Italians that listen to the Buono Tomatosong can immediately understand that it's a Tarantella, a south Italian dance that mimics the effects of chorea (an abnormal involuntary movement disorder). In the comics, Romano suffered from that disease when he was young...see? Everything in Hetalia has a reason!
Especially since South Italy is prone to earthquakes.
The dub uses this trope word for word when Romano calls Germany Hasselhoff as an insult.
Russia is also pretty popular amongst American and Japanese fans. Wonder why?
Mind Game Ship: Whenever someone ships Russia with anyone else, the fic usually turns out like this.
The best example would be the "Bloody Sunday" strip, in which Russia finally snaps and starts GUNNING DOWN his own people as they're rioting in the streets ("If they hate me, they're not Russian.") before turning to Lithuania and stating "We don't want children who can't play nice, do we?".
The final fight in the movie, as well. Throughout the movie, the nations being assimilated was treated as quick, random, and comical. In the last fight, it's down to the handful of remaining characters to fight to survive, as they're overrun by aliens. They get picked off one by one, scared and screaming for each other. Unlike previous conversions, they transform slowly and call out in terror the entire time. And when they are assimilated, they still look kind of like their human selves, remain frozen, and have the aliens just walk around them creepily.
England's creepy Black Magic and anything related to it.
Denmark is often seen doing this in fanon, as well. How else could he rule the Kalmar Union then?
Older Than They Think: Hetalia was not the first series to attempt to do anthropomorphic depictions of nations. It just happens to be the most popular.
One Head Taller: The 2 cm height difference between America and England tends to be exaggerated by both fanartists and the author himself. (In fact, England is usually drawn much shorter than he actually is - according to the height info, he's the same height as France. This is possibly because his personality is very reminiscent of The Napoleon.)
England's height may have been retconned in the comic: in one strip young France teases England about being small. Sure, they're both children at that point, but little England is very short.
A lot of popular pairings fall under this trope in canon. Just take a look at Sweden and Finland, Greece and Japan, Korea and China, Seborga and Monaco or Russia and China.
Yaoi Fangirls also have a tendency to SHORTEN "submissive" characters' height, which is connected to Wimpification. For example, they shorten Finland's height a greatly exaggerated amount, sometimes to the same height as Sealand.
Italy and Germany. Germany is 8 cm taller than Italy, making for some awkward situations (such as when Germany is too tall for Italy to hug, so Germany kisses his cheeks instead) but Italy is not so short that Germany has to rest his chin on him like some fanworks depict.
One of the more mind-bending offenders is when America/UK is reversed and England is made taller than America. Although often America is also made meek and wimpy at the same time. Which make things... confusing.
Bizarrely inverted with Lithuania and Poland. Even though they have a greater height difference than Germany and Italy (10 cm), most fanarts show them lacking any height difference.
The Japanese fandom has Joker for America x England (Alfred F. Jones x Arthur Kirkland.) The reverse is 過剰 (pronounced ka-jo). In the west, USUK (or UKUS, depending on the seme-uke dynamic) is much more common.
There are actually a lot of these for various pairings (let's play the "how many pairing names can you decipher?" game!): AmeBela, AmeCan, Ameripan, AusHun, DenNor, DenSu or DeSu, Franada, FraSey, FrUK, GerIta or Gertalia, Giripan, KoHo, LietPol or PoLiet, NiChu, NorIce, PruAus, PruCan, PruHun, RoChu, RusAme, RusLiet, Spamano, SuFin...
Or a Psychopathic Manchild or even Bespectacled Bastard Boyfriend who treats Japan horribly during/after WWII. Sometimes this is done to send Japan running off into the arms of someone else, but other times it seems that the fan authors truly believe that America would actually act like that towards Japan. While Japan initially resented America, he eventually warmed up to him during Westernization and is clearly good friends with him in the post-WWII strips. You would think that would signify that the events at the end of WWII are far from the be-all end-all of their overall relationship, right? Apparently not.
The infamous "Nazi Prussia" fanwork trend, in which Darker and Edgier fanworks make him an insane Nazi who beats/rapes/betrays/abuses/etc. his fellow nations - specially Germany, Austria or Hungary.
Either that, or he's shown as The Ditz and Jerkass whom everyone hates and/or abuses.
Some people overexaggerate Belarus's bad traits to make Lithuania look more woobie-ish than he truly is or to discourage the Russia/Belarus pairing.
Turkey might not have the most agreeable of personalities or the best of relations with Greece or Hungary, but some fanworks turn him into a complete asshole who will smirkinglymanipulate, abuse, and rape others solely to "put them in their place", whether because these fanwriters love The Masochism Tango of Turkey/Greece or Turkey/Hungary or are enamored of the idea of Turkey as a Bastard Boyfriend with a White Mask of Doom.
Scotland hasn't even been in the anime yet, but it doesn't stop some fans from making him a Big Brother Bully or downright abusive (usually to England, but Wales, Ireland and other countries get their share of it, too.)
The Scrappy: While not as open as in Korea's case, you can bet that in a poll about disliked characters Sealand will have a "top" spot.
Rescued from the Scrappy Heap: Fans generally started liking him more mainly because he seems to be the only nation that was able to defend himself against the mysterious figure and question him with no problems, even striking an Intergenerational Friendship. In fact, a lot of memes concerning him exploded because of said incident.
Due to being a micronation and not a real country, as well as some fans not liking her bratty personality, Wy's debut quickly earned her this position along with some accusations of being part of a Spotlight-Stealing Squad.
No discussion of The Scrappy would be complete without Korea, who was raked over the coals by fans disgruntled about the Korean Moral Guardians forcing the cancellation of the Hetalia anime's TV broadcast. Fortunately, this seems to have all but died down with the passage of time; nowadays it's a lot more common for fans to lament that Korea isn't in the anime instead.
Or Japan, who was hated by people who called him a Misplaced Nationalism-fueled Canon Sue that was ruining the anime after every episode he appeared in. Or took personal offense about him being as beloved in Japanese fandom as Canada was in Western fandom. Or claimed that him not being depicted as a monster or his Imperial Japan atrocities not being portrayed in graphic detail in a series focused on the light-hearted side of history meant that Himaruya was "trivializing" history. It was mainly limited to a Vocal Minority, but they kept on finding the stupidest reasons to bash him; there was even a post on the Hetalia comm that bashed Japan as a "shojo harem manga heroine" to promote Turkey/Poland. Fortunately, like with Korea, the hate has quieted down over time, probably because Japan having a minor or supporting role at best in the comics means that the Vocal Minority can't call him a Spotlight-Stealing Squad by any stretch of the imagination.
A more canon-supported example is Germany for Italy, who used to be in love with the Holy Roman Empire. To make things even more interesting, there are hints that Germany and the Holy Roman Empire may actually be the same person.
Ship-to-Ship Combat: In the end, not even this fandom proved to be immune to this. See main entry for details. And we're not talking about their navies. (It reaches the point where one of the very first reactions to a new character's appearance is people using him against another pairing.)
Squick: France's treatment of Seychelle's probably doesn't count as Lolicon if he only hits on/gropes her when she's a teenager.
Tastes Like Diabetes: How some fans (particularly the older male crowd) see the younger versions of the nations, especially Chibitalia and the Holy Roman Empire. Some newcomers to the anime also tend to be disgusted and taken aback by the idea of these little guys and moe having business in their "history" series.
He also stomped on poor Italy's head when he did something wrong or forgot to do something, and locked him up for "stealing" food that was actually a gift from Holy Roman Empire.
Viewer Gender Confusion: Hong Kong has been confirmed as male, but some fans are still confused. As for China, the author himself lampshades this trope in regards to him by listing him as the only female Allied member on the official character chart... before adding a "Not" on the end.
The audience isn't involved and is instead switched with HRE (and a few other countries at the time, until Italy grew up). Mainly, HRE always thought that Chibitalia was a girl.
New Zealand. Though now confirmed to be male, there was a lot of back-and-forth speculation when the character design first came out.
Wangst: "Einsamkeit (Loneliness)". From the few lyrics we know, it's played for laughs.
What Do You Mean, It's Not for Kids?: Many non-fans and a few fans have mistaken Hetalia for something meant to educate children, especially the anime. Partially because the anime was supposed to air on a channel called "Kids' Station" (protests got it pulled from TV and made into a webcast.) However, this isn't a sure thing as Kids' Station plays anime for an older audience later in the day, similar to what Cartoon Network does.
Some fans have ragged on China for his "girly looks" and "girly voice". Even though the guy has fricking super strength and martial skills in the anime. Apparently being able to disarm and overpower two very skilled opponents (who are wielding a katana and a gun) with nothing but a WOK isn't at all impressive... just because of the aforementioned feminine appearance and voice.
Poland's Keet behavior and penchant for ponies and skirts makes him hated in some circles.
Austria haters (or more specifically, the die-hard Prussia/Hungary and/or Romania/Hungary supporters) frequently exaggerate his Non-Action Guy traits in order to make him unsuitable for the Lady of War Hungary and thus leave her free to go off with the much more battle-oriented Prussia or Romania.
The Woobie: Oh Canada, he might be ignored in canon, but fans have not failed to recognize him.
And then there's China. No matter how hard he tries, no one ever seems to respect him. Even his allies pick on him and order him around. His adopted Japan stabbed him in the back for seemingly no reason!
Little England crying about how lonely he is, or a grown-up England getting his heart trampled on by America... The fact that he is mocked, ridiculed and disrespected by nearly everyone doesn't help.
Oh, Lithuania. The fact that Lithuania is the suicide capital of the world bodes ill for his future, to be sure.
Italy, mostly due to his own incompetence (even the title says so!) but that doesn't make him any less sympathetic.
Doubly so in his Chibitalia days. His loving Grandpa Rome falls/vanishes, leaving Italy and his brother to be picked on by stronger nations. Italy is finally captured by Austria and forced to be a servant, while Romano is sent to live with Spain. Then, just as Italy starts to warm up to Holy Roman Empire (who he'd previously been terrified of), the HRE leaves to enter a war. Italy's saddened by this, remembering how hurt his grandfather was after a life of battles, but promises to wait for Holy Roman Empire to come back. Except he never does. And while it looks like it's possible that he survived to be present-day Germany, Germany still can't remember anything so Italy still thinks his first love is dead.
Its woolseyisms are popular enough that scanlations seem to take inspiration from it, such as adapting America's wording to be somewhat looser than earlier translations (which were already casual), therefore resembling his Totally Radical speech pattern in the dub (uses of "Dude," "Respect," etc).