(oh no i don't ship them because they're common! I ship them because i love them! Like USUK is just funny and smutty all at once, Gerita is pure fluff and is my OTP i fell in love with Hetalia because i came across a Gerita fic purely by accident! And Spamano because i am just like Spain and my girlfriend is just like Romano.)
(Still. =w= So common. I fell in love with Romano's voice, which is how I came into the series. RusRoma started as a joke between my friends and I, but then I began to notice how much they had in common, their history, and everything. UsUk because my friend shipped it, England has a crush on America, and their relations. Gerita because of the Holy Roman Empire as Germany theory (I honestly don't find Germany attractive). But hey, I tend to look further into pairings via history and not just what looks cute and/or canon to the series.)
Besides Trading, they really have nothing in common. But I ship it for the hell of it. 8D Kinda like PruChu too.