In World Stars, 281 to 284, Prussia realizes that Romano gets a little stunned and excited about his stories of his knighthood.In another strip, Prussia observes Romano working, surprised how he is a hard worker. He asks if Romano doesn't have the money to buy shoes, and Romano replies that it's just that he prefers to use his money for more important things. In addition, Romano seems to feel comfortable enough to sleep in the presence of Prussia.
In a strip, called "The one that wasn't there", Romano is depressed that he didn't get the main character in the movie and Prussia extends his hand to him, saying that he should make his own movie "A movie that we truly want ...!"
In addition, Himaruya likes to relate the characters in illustrations where Prussia seems to want to provoke Romano, both calling him "Ita-chan's older brother" and commenting about him being the smallest of the four.
Both Prussia and Romano have younger siblings, and are often overlooked in favor of their brothers. Even though they are complete opposites, they are said to be able to understand each other.