So I'm gonna involve myself into shipping and write an idea for this one: SerbRoBul.
Basically how I see it, love triangle, set in high school. Aleks (aka Bulgaria) has a crush on Vlad (aka Romania) but he isn't brave enough to confess due to his back thought thinking he would ruin their friendship, he also doesn't know anything about Vlad's love life. Vuk (aka Serbia) is a childhood friend of Vlad, they have known each other way before Vlad and Aleks meet. However Vuk and Aleks meet separately without Vlad knowing. They ended up in a "friendship" trio somehow, although Vuk and Aleks fight most of the time while Vlad happens to stay in between them to calm down the tension. Ever since Vuk found out Aleks has eyes for the romania he never stopped teasing him about it, in the worst way he could think of, as in he sometimes will pretend to tell Vlad about it and freak Aleks out, other times getting flirty with Vlad purposely making the bulgarian angry and jealous, or prank Aleks and tell him he already found someone (lying obviously), but the serbian will soon find himself in the same position as Aleks and start crushing over the romanian. By that time, the whole teasing was less about actual tease and rather more about attempts to keep the bulgarian away. Now the reason why Vuk wouldn't confess is different (it has to do with his social status). Vlad doesn't know shit of what's going on with these two but them acting weird around him it's pretty much obvious, tho he doesn't get involved in their conflicts anyways.
And I have no idea how this thing should end. 🤷♀️ but that's about it for now.