In the former Yugoslavia, there used to be a joke about how to tell the difference between a Serbian girl and a Croatian girl: If you tell a Croatian girl she is pretty, she smiles, but if you say the same to a Serbian girl, she scowls.

Well, in 2013, smiling Croatia joined the European Union. In the same year, scowling Serbia, after much heavy diplomacy and a traumatic change of national policy, managed to became a valid candidate for a membership process that will have Serbia in the EU probably by 2020. The two girls, the scowling one and the smiling one, will finally belong to the same political arrangement again, just like they both used to belong to Yugoslavia, before they ruined it. Nowadays they are divided by a heavy border, even though the rest of the world can't possibly tell these two girls apart unless they offer them a compliment.

When dropping by smiling Croatia and scowling Serbia, one notices similar changes in their ways of life: The roads are better, there is more order in public spaces, buildings have facelifts and paint jobs, and the restaurants serve nicer food. But when speaking to the Balkan locals, those in the EU or out of it, one hears about the darker side of EU integration: less local power, less money, less identity.

Serbia these days has truly weird, ecstatic politics. The current prime minister belongs to the party of Slobodan Milošević, the deceased malefactor who brought war to the Balkans in the 1990s. Despite that, there's serious talk that he might get the Nobel Peace Prize together with the Albanian leader because of the Kossovo negotiations. He remarked with startling frankness: I made that war, so I am the one entitled to sign a peace treaty.

In downtown Belgrade a show opened a few days ago: photos of war-crime atrocities committed in Kosovo by the Scorpions, a Serbian paramilitary group, against Albanian civilians. This was a high-risk public event, with grieving families, a heavy police presence, threats by the usual hooligans and nationalists, the well-known story.

Then the prime minister arrived, to everyone's astonishment, and shook hands with everybody. The organizers, the surviving members of the destroyed families , the alienated youth -- he didn't seem to play favorites; he just congratulated them in front of many cameras. There are no "our" and "their" victims anymore. And as if by some work of destiny, the goddess of revenge, Nemesis, the leader of the Scorpions was killed with his family in a car crash on his way back to prison only a couple of days later!

It seems incredible to admit this, but the work of Serbia's long-isolated peace activists is now the foreign policy of the country. If the prime minister of Serbia snatches the Nobel Peace Prize out of their hands, it's still a major victory.

Then there is the vice prime minister of Serbia, who is equally remarkable. He's a prominent member of the revived Radical Party, a formerly loathsome group whose notorious leader Šešelj is still in The Hague awaiting trial for atrocities. The vice prime minister stunned the nation when he frankly declared that his party too was responsible for the killing of a dissident during the Milošević era.

And then -- since he's in such a good position to know -- he insisted that he will get to the root of the issue and arrest and punish all the responsible parties. The case was a state murder of a prominent journalist; everyone has known for years that the government killed him, but there's been a polite pretense that the assassins must have died of old age.

In smiling Croatia, by contrast, reactionary Catholic sentiment voted sharply against gay marriage rights, a slap in the face to the progressive values of a united Europe and a setback for the hard work of the activists. You'd better not tell that Croatian girl she's a pretty lesbian.

In Serbia, the gay pride parade was forbidden again this year. The prime minister said he wasn't sure that he could protect the gays from hooligans. Maybe after he wins the Nobel Peace Prize, gays will somehow feel safer.

The paradox of Balkan history is that killers become rulers, warriors become peace makers, sisters become enemies, then sisters again on new terms, and law exists mostly as a hoax to make this vicious circle seem like local politics as usual.

In 2014 the world will mark the centenary of World War I. The Great War started in Sarajevo, in the Balkans, when a teenage Serbian anarchist from the Black Hand militia killed the Archduke Ferdinand and his wife. This vicious act proved a fatal blow to the Austro-Hungarian Empire. After a hundred years the polemics still roll in: Was Gavrilo Princip a liberator or a terrorist, or maybe a presentiment of the modern suicide killer? Was his motive idealism, black resentment, or a lust for destruction? Papers, plays, and books have been written on the identity issues of Gavrilo Princip.

In Belgrade, Princip has his own road, descending from the seven Belgrade hills to the banks of the two rivers Sava and Danube. Suppose that young Gavrilo Princip paid a compliment to the Croatian girl today, as well as to the Serbian one. Who would scowl? Who would smile? Who would pull the trigger?

Maybe those two girls could somehow offer this historic terrorist a chance to drop his gun, in a clinch between a kiss and a scowl, a carrot and a stick, so that he can live in a country without borders instead of killing and dying for farfetched ideas.