I love this picture so much. ^^
I have this headcanon where they were all best friends when they were little.
Romania and Hungary would fight so much about who was manlier, but then Prussia would break their fight up saying that, of course, he was the manliest because he is awesome.
And then Hungary and Romania would just look at each other and grin, and then start to tease him until Austria stood up for him, but then Hungary would get really possessive, and then Romania and Prussia would get jealous (Romania because Hungary wasn’t paying attention to him, and Prussia because, hell no woman, lay your hands off my man).