A common misconception is that he is definitely Serbian. i tend to disagree. first, there isnt ANY proof saying he IS Serbian. He speaks Serbian? he fought the "War" (obviously Yoguslav Wars)?, Ok. He's from Yoguslavia obviously. now where in Yoguslavia? how can you be so sure he is Serbian? why not.... Croatian? The language spoken by Montenegrin people, Serbians, Croats and Bosnians is called Serbo-Croatian, and sometimes, Serbo-Croatian-Bosnian. Sam Houser clearly said that he has no clear nationality, so saying he is Serbian definitely or Croatian definitely is wrong.
what we DO know about him.
1. He is definitely a Slav.
2. most likely Yoguslav (The war, working across the adriatic, speaking Serbo-Croatian)...
3. now he cant be Bosnian or Slovenian because he doesn't show anything Slovenian. now since he speaks Serbo-Croatian its possible he's Bosbian, and as it appears, he is most likely not a Muslim, so he isnt Bosnian.
4. He isnt Macedonian because like Slovenian, he doesnt seem like one.
5. Finally, he is either Croatian, Montenegrin or Serbian.
By this information, He could be whatever you want him to be, Serbian, Croatian or Montenegrin.