Sure! I’ll show both sides just to be fair, though. 

1)  Prussia and Fritz.

The two shared a very close relationship. Prussia viewed him
as a father figure and gets depressed at any mention of him in the present. He
also sleeps with a photo of Fritz on his night stand.

Source: Hetarchive, Notes & Etc + Hetarchive, April Fools Event 2009 + Hetarchive, Christmas Event 2011. 

2) France and Napoleon.

France oversaw Napoleon’s rise to power, similar to a father
figure.

However, he later becomes terrified of him. The context is
that during Halloween, ghosts of past bosses are able to visit Earth. Napoleon
becomes furious because he thinks that France has become too soft.

Sources: Hetascanlations, World Stars Chapter 358 + Hetarchive, Christmas Event 2014.

3)  Spain and Queen Joanna

She angrily berates him for wasting too much resources on
Romano.

Sources: Hetarchive, Boss Spain Doesn’t Understand 1 & 2. 

4)  Russia and Peter the Great

The two both underwent a process of Westernization. Russia
was sent to France to study his culture. There was a lot of intermingling with
French nobility at the time. 

Sources: Hetascanlations, World Stars Chapter 298 & 299. 

5)  England and Queen Elizabeth II

She encourages him to give America a gift for his
bi-centennial. She also warns England not to ruin his health, as he becomes violently
ill every year on America’s Independence Day.

Source: Volume 4.