Turkey has been trying to make headway on its stalled membership bid at a summit with the EU.
But criticism of President Recep Tayyip Erdogan's perceived authoritarianism and Ankara's intervention in Syria make for an uncomfortable backdrop in Bulgaria's Black Sea port of Varna.
Bulgaria is keen to keep ties as positive as possible with its neighbour, but amid reports that its extradited at least one opposition activist back to Turkey, it's facing criticism.
"What the Bulgarian government did with these political dissidents goes against all European values," said political analyst Antony Todorov, from the New Bulgarian University.
"Dignified conduct sometimes requires a more firm reaction. Otherwise we wouldn't be partners. No one would take Bulgaria seriously, especially in Turkey."
EU leaders were expected to award new funds to extend a deal on Turkey taking in Syrian refugees.
But not much more than that, with the EU membership bid still ailing. That process is focused on rule of law, press freedom and economic reforms.