The following guide is meant to contain a list of this forum's particular norms - every forum tends to interpret Hetalia just a bit differently, and this one is no exception so this is meant to help you understand the quirks here. Unlike the other guides in this section that are along the lines of 'here are some headcanons you can use if you want to, but you don't have to', these lean more (but not necessarily completely) in the direction of 'have to' in order to keep everyone on the same page. That being the case, please speak up if there is anything that you feel needs to be added, edited, or removed - this will likely need changes as time goes on as forum norms tend to not remain static.
Auras Every nation, territory, etc. has an aura. Auras are invisible, but they can be felt by other nations, territories, etc. The size and 'feeling' of someone's aura directly corresponds to their overall power. This means that a powerful empire can be felt while they're still out of sight, but a tiny micronation may not have an aura that can be felt at all. In fact, one of the main ways that nations identify each other as being a nation and not a human is because of their auras - that's one of the reasons why micronations have trouble getting international recognition.
Auras are to a certain degree distinct - nations can recognize their closest friend's, family's, and even extremely well known enemy's auras without looking, though this is difficult and a sign of extreme familiarity. Though it is possible to guess who someone is (or isn't) based on an aura - for example, if you sense an extremely strong aura headed your way but there's only one nation with that strong of an aura likely to be in that location, then you know who it is. And even if you don't know who is likely to be in the area, you do know that it isn't any of the weaker nations. One tends to lose this ability when a large number of nations gather, however, as so many auras in one location makes it difficult to pick one out in particular - it simply feels like there are a lot of nations present.
Humans do not have auras and can't detect them aside from the aura of their own nation. And even then, they're not generally very familiar with auras so they don't necessarily know why they're feeling what they're feeling. The degree to which they detect their nation's aura also depends on their level of patriotism - and most humans are quite patriotic. In fact they're usually more patriotic than they realize as patriotism isn't about believing that one's nation is perfect, but to what degree they care about their nation and what happens to it.
Nations can, and usually do, use their auras when speaking to their people - this causes their people to take what they say seriously. Especially if what they're saying is some sort of an order - the human gets the very strong sense that their nation indeed is asking them to do something. Which may weird them out if their nation is a toddler, but they'll generally do it anyway. Many nations attempt to eliminate the weirdness by dressing like some high-ranking official so that it seems only natural for others to follow their orders. But then again, most nations will still run into 'aren't you a little young to be a five star general?' problems.
Injuries, etc. The current physical state of the personification of a nation, territory, etc. does not always perfectly match that of the people they represent, but either quickly or eventually they will match up.
Specifically, if something bad happens to the personification, nothing bad happens to their people. And if, on the whole, their people are doing well they can heal from the most devastating injuries - including being killed. In addition to being able to heal from anything, they can also heal faster than a human would. However, how fast and how well they heal is dependent upon their people - the personification of a big and healthy nation can heal from being blown into pieces in about a week. And even if they've been blown to pieces they will heal perfectly - no scars or anything like that. The smallest and weakest nation can pull themselves together in about six months, assuming that they're doing well otherwise. Of course just because they can heal doesn't mean that such injuries aren't just as painful, though if the injuries are especially devastating the personification becomes extremely tired and will sleep until they're healed unless extreme efforts are used to wake them. On a similar vein they do not starve to death or die of dehydration but do get extremely hungry and thirsty if they don't get anything to eat and drink.
If something happens to the nation but not the personification, on the other hand, they feel it instantly. Poor economic conditions cause illness, physical damage to the country (either the infrastructure or the land itself) causes injury, losing people causes overall weakness, and low morale causes a poor mood. All of these affect the personification instantly and do not go away until the country itself recovers. So if a personification is not afflicted by any of the above but something happens to the country then they will feel it immediately - which means that they may suddenly become injured while they're standing there doing nothing. But in practice the personification is usually already injured at that point - unless they're being caught completely by surprise they're usually aware that they're being attacked so they're on the scene attempting to prevent the attack. And if they fail they usually get hurt in the process, and the injuries they receive become tied to the damage done - they do not heal until the damage is repaired and these injuries often leave behind permanent scars (though they may fade in time as the event is forgotten).
Where Nations Come From When two nations love each other very, very much... Actually, that's not usually how it works. When you get down to the root of it all, nations are ideas created by humans. The concept that one place is different from another and that the people in the first place are a different group from the people in the second place is entirely manmade. Because of this there is nothing biological about the origins of a nation, territory, etc. Instead in the beginning they're merely an idea held in someone's head that a particular place is separate and distinct from every other place - and they often give it a name. Now, this idea can be held by only one person, and that alone is enough to sustain what may very well become a new nation, though that's a fragile existence at best because if something were to happen to that person or even just the idea in their head then that idea would disappear without developing into anything.
But if that idea continues and especially if it gets passed around by others, the existence of it becomes more assured. Especially if this idea of a place gets found by an already existing nation. Some might accuse nations of being selfish, land-grabbing jerks who want to lay claim to everything, but that's more true of Bosses - most nations simply find these newly formed idea-chibis to be too adorable to not take home with them if they can. Wars have been literally fought over them, in fact.
However, that alone does nothing to help a little chibi nation develop further - what they need first are people. That they have people isn't a given - a person only belongs to a nation if they believe that they do. It's possible for someone to belong to more than one place, but there are places that are uninhabited or that are inhabited only by people who see themselves as visitors. A little chibi nation in this situation can't grow, and they also can't speak. There are some unfortunates who are uninhabitable islands or places of that sort who seem likely to be in that situation forever. But it only takes one person belonging to them to change that - then they're actually capable of developing into something more.
How much more depends greatly upon their situation, especially if another nation has taken them in. But if they get a number of people, those people tend to like to group together. A culture unique to that place begins to develop, even if it's heavily influenced by the nation who took them in. What was once a silent, infantile chibi-child begins to have a unique personality. Still more and the people feel the need to organize themselves and establish rules - the chibi begins to grow up.
Because of these origins, the family ties that nations feel for each other aren't exactly genetic, even though there may be a family resemblance - nearly everyone is 'adopted' and the way that they describe their relations are more based on their feelings for each other than anything else. But there is a difference between merely being taken in by a larger nation and being seen as family - which is which seems to depend on the whims of the larger nation in question. If they decide that a particular chibi-child is family, there's usually quite a bit more investment in the child's development and they're more likely to grow up into a big, strong territory that is ambitious enough to secede. If the child is less encouraged, they're more likely to grow very slowly and be more of a humble servant - though exceptions to this can be found everywhere.
There are also exceptions to gaining family through adoption. In fact, even though it's more common various cities, territories, and nations to just 'happen' it's certainly not unheard of for these to be created intentionally. And though it's most common for nation to feel a sibling relationship with their family members that they've found - as they take responsibility for their sibling but not responsibility for the existence of their sibling - they're more likely to consider a family member that they created on purpose to be their child. What's more uncommon is for such a child to have more than one parent, but it can happen if a place is intentionally created to be a cultural mixture - though the nations involved are usually only daring enough to make a city of that nature. Cultural mixtures are usually a bit... tricky. More often when cultures share space one will put itself in charge of the other and that will be that.
As a footnote: Since manmade objects large enough to be considered their own place, separate from any others, are a relatively new phenomenon the nations themselves aren't quite aware that these too can become nations in the right circumstances. About the closest thing they had in the past were certain ships that went rogue and didn't have loyalty toward any nation - but ships aren't exactly permanent structures so though a chibi-child might appear for them the nations would never consider them to be a nation. In fact the idea that one needs actual, physical dirt with their name on it is very entrenched. But with certain technological advances at present and on the horizon they're probably going to have to abandon that idea - though it might take a hundred years or so for them to do that. In the meantime it's worth noting that manmade objects can become independent if they end up on a situation where they don't officially belong to another nation.
