From Wikipedia
They are one of the few. However, less than 90% of the Serbs remained in Croatia. What would be the implications if the Serbs there went to Srbija or Bosna? Since Oluja or operation Storm, they went through Bosna and Srbija.
This could be trivial. Some members of the Serbian basketball team was born in Croatia. Notably:
Predrag "Peđa" Stojaković
Milan Mačvan
Kosta Perović
Zoran Erceg
Đorđe Gagić
Duško Savanović
One exception is the Bosnian Serb Aleksandar "Saša" Vasiljević who was born in Croatia.
In actuality, the Serbs settled in modern Croatia during the 7th century which is current day former Yugoslav republics. Through building kingdoms and empires, monasteries and churches belonging to the Srpska Pravoslavna Crkva, invasion by Ottoman and Hapsburg states, Catholicizing most Serbs from Dubrovnik, and through the Kingdom of the Serbs, Croats and Slovenes/Jugoslavija, they survived like nothing happened.
Then, the Nezavisna Držva Hrvatska imposed their anti-semitical and barbaric war against the Serbian Orthodox population living in Croatia. Serb hunting season started, as Ante Pavelić, Alojzije Stepinac and others supported this fascist state as mentioning "Bog i Hrvati" or "For God and Croats". 700,000 and as more as 1,400,000 were killed, mostly Serbs of course. Few Jews were saved because of the Vatican's rescue efforts like how they are doing also in Poland.
In socialist Yugoslavia, Serbs born in Croatian soil are the ones who are serving as police, government and economic minsters, declaring themselves as Yugoslavs.
Then came, the war. Both Croats and Serbs were fighting for territory and representation. As what i know, when Croatia seceded from Yugoslavia, the Serbs want to break from Croatia, like how West Virginia, who was loyal to the Union separated itself from Confederate Virginia. As war rages, both sides committed atrocities. Siege of Vukovar, destruction of Serbian churches and monasteries, Serbian homes were destroyed or forcibly taken by the new Croatian settlers and costing the lives of Josip Kir and Milan Levar in the process of their fair and just Croatia.
USA came to give Croatia total independence, bombing the Krajina Serbs into submission as what is called operation Storm. A storm that lasted a few days, resulting to a death of thousands and quarter of a million ethnically cleansed Serbs escaping to Srbija or other countries as Slobo and his generals abandoned them. Some of them are currently in Serbia or represented the country in all fields while the Croatian Serbs were left served for Croatia. Here are some:
Marko Popović-basketball player
Arijan Komazec-Basketball player
Milorad Pupovac-politician
Vojislav Stanimirović-politician
Željko Jovanović-politician
Branko Grčić-politician
Milanka Opačić-politician
Slobodan Uzelac-politician
Here is just a short summary of the history of Croatian Serbs. I don't know much but this is what truly and is happening now.