Russia/Ukraine is a slightly canonical pairing in Hetalia: Axis Powers, consisting of Russia and Ukraine holding feelings for one another. It is one of the few relationships that are truly incestuous in the series. However, it is not very well known, so the fans of this pairing are few.
Russia's Big and Little Sisters
Russia introduces Ukraine first, describing her as very nice, but not very pretty (the opposite of Belarus, whom he called pretty, but not nice). He also describes her as being very poor, and because of this, her gigantic breasts (which apparently make her back hurt from being so heavy) are real. The scene then cuts to show him and Latvia standing outside Ukraine's door, knocking and asking Ukraine to come out and pay the gas bill. Ukraine does not answer, however, the 'boing' sound her breasts make can be heard through the door, so they know that she is inside. Inside, Ukraine's boss quietly signals for her not to open the door. Ukraine turns around, crying. She quietly apologizes to Russia and promises to pay him back when she gets rich.
The scene changes back to an upwards angling on Ukraine. Russia comments that with "those collosal knockers of hers" (her breasts) she ends up being a target a lot. He also mentions how she is very fun, but is also weak because she is a crybaby. The scene cuts again to show Russia poking Latvia in the face when Ukraine comes up behind him at a distance, claiming she has food for Russia. She says how she used fresh milk to make it for him, but then stops and begins crying when she remembers that her boss has forbidden her to speak with Russia. She runs off crying, expressing her hope that they'll be able to see each other again someday. Latvia wonders what Ukraine's crying was about, while Russia simply looks sad because of her leaving.
In another strip, Russia remembers the time when Ukraine left his house forever. He comments how she joined the UN and had begun looking for friends in the world. However, it appears she had been having some trouble, as she was crying and asking if anyone would be her friend. Russia, who is standing only a few feet behind her, tries to get her attention. Later, Ukraine is shown to be the third country to leave Russia's house (the Soviet Union), and she does not return, unlike Belarus, who had left around the same time that Ukraine had. Belarus apparently freaks Ukraine out, as she intimidates her older sister much like she does everyone else.
Later on, Russia sits on a park bench, wondering where it all went wrong. He remembers back to when they (Russia, Ukraine, and Belarus) were all children. He and Belarus comment on how cold it is, prompting Ukraine to go and get something to help with it. Ukraine comes back with her favorite scarf and gives it to Russia "So I can always keep you warm. (Of course, Belarus does not like this.) However, she soon smiles and says that all she wishes for in return is control from the Black Sea to Poland (Kievan Rus inheritance rights). Russia comments on what a schemer she is.
Carrot and Stick
In Ukraine and Belarus's character song 'Carrot and Stick", it is hinted that Ukraine holds romantic feelings for Russia. She mentions that, in her dreams, she and Russia would see each other, and how much she would like to hug him again. When Belarus accuses Ukraine of taking Russia's affections in the song, Ukraine replies, though somewhat sarcastically, that she is sorry for being a bewitching older sister. In addition, there is at least one part in the song where both she and Belarus sing "let us finally become one together", meaning that she would like to do what Belarus outrightly wishes, though she is more quiet about it.