Hungarian-Serb Relations have developed substantially in the past 15 years:

•Signed Strategic Economic and Military Partnership between Hungary and Serbia
•Budapest–Belgrade Railway Infrastructure Project Valued at €2 billion
•Highway, Oil and Gas Interconnections Valued at €5-6 billion
•Trade Volume Surpassed €3 billion Annually

Hungary-Serbia have a history of Military Alliances since the 13th Century. The Second Battle of Kosovo 1448, Siege of Belgrade 1456, was fought together with the Hungarians and Serbs United against the Ottomans.

Vojvodina, a formal region of the Hungarian Kingdom is given substantial autonomy under the current Serbian Government with 6 official languages including: Serbian, Hungarian, Slovak, Romanian, Croatian and Rusyn.
Of all formal territories of the Kingdom of Hungary, this region offers the most significant autonomy to its minorities.

The Two Nations are at a Crossroads together in Central Europe with a shared fate. Both Nations are attacked by the European Union and its subjects which are also currently in power in Croatia.
While crucial supplies of oil and gas are harder to come by due to the War in Ukraine. The Croatian Government offers an alternative at 5x the Market Price meant to impoverish the nations of Hungary and Serbia.
This forces the two Nations to unite against those that threaten their sovereignty. Which brings into the creation of the Hungary, Serbia, Slovak and Srpska Alliance countering Albania, Croatia, Kosovo and Bosnia.