The two were once under the control of Denmark, but Sweden got sick of living under his rule so he left the household. Finland, wanting freedom as well, decided to follow Sweden. Although happy to be away from Denmark, Finland first thought of Sweden as intimidating, and planned to run away from Sweden. However, after Sweden embraced Finland to keep him warm, Finland came to the conclusion that Sweden was just hard to communicate with.
When Finland met his old friend Estonia again, Sweden introduced himself and claimed Finland was his "wife". Finland thought it was a joke, but Sweden was actually serious about it. Sweden tried to get Estonia and Latvia to move in with him so Finland would have more friends, but only managed to get partial custody due to Poland.
At one point, Finland got a white puppy, and suggested giving him a variety of bizarre names. He and Sweden eventually compromised and agreed to call the puppy "Hanatamago" ("hana" is Japanese for flower and "tamago" is Japanese for egg). During their life together, Sweden also altered some of his spare clothes to give Finland more due to the 12 cm height difference between the two. When Finland said it would be nice to have children, Sweden said he would do his best, confusing Finland.
Sweden bought custody of Sealand on eBay and became his father figure. It is unknown if Finland was involved in raising Sealand as the three were only shown together in one strip.
Sweden and Finland took part in the Hetaween 2013 event, where they might have arrived together (along with Hanatamago). When the Nordic countries were asked if they were lonely without wives, Sweden replied he would like to marry Finland. Finland asked Sweden to clarify. Later, Iceland asked Finland, whose costume was a white dress, if the costume was meant to partner Sweden's, who was well-dressed. Finland blushed and denied it, although he had to have a three-day conversation with Sweden about the costume.
Behind the Scenes
Hidekaz Himaruya, the creator of Hetalia, confirmed Sweden was homosexual, and that he only acted that way towards Finland. Sweden is the only character whose sexuality has been confirmed, although other characters have hinted or implied sexualities.
SuFin is a popular pairing in Hetalia and the most popular ship for both characters. In the fandom, Finland is often seen as Sealand's "mother" figure.
On AO3, it is the most written ship for both characters, and the seventh most written ship in the Hetalia: Axis Powers fandom.
- Their birthdays (June 6 and December 6) are on opposite sides of the year. This, however, is a coincidence as their birthdays were chosen to match the national days of the countries.