Russia was, since childhood, sort of trouble-maker. So, USSR, hired you to be a kind of bodyguard for Russia. He's not a child anymore, but still acts like one. And you accepted. That guy is paying you a lot of money after all

You two were walking on the street, after Russia convinced you to buy him a shark plushie

"Well, thanks for buying me this! But, when do I get my vodka?"

he had that pouty face. You took away his vodka, since it was better for his health, to stop for a time