With any PoD you want, create a scenario where instead of West Germany annexing East Germany, the opposite occurs.
Stalin wants to have the industrial areas in the Ruhr, so the Soviet zone of occupation is the northwestern part of Germany (the OTL British zone and the northern French zone), and becomes the DDR, while BRD is established between the ATL Soviet zone and the Polish zone.
Perhaps American Bremen will become the new West Berlin equivalent, if the zones otherwise are as OTL. And the Russians have the OTL British sector of West Berlin - a reverse communist enclave, now this is fun!
The BRD capital stays in Berlin, but what city will DDR chose? Hamburg or Hannover or ... ?