Norway comprises, more or less, OTL Norway.
Southern Norway was invaded by the Third Reich in 1940, when the government (Parliament and Royal Family) were moved to Trondheim, protected by the United Kingdom and its Royal Navy.
The German government integrated southern Norway as a Reich state (Land), preserving Norwegian culture and language, but Germanizing the institutions. However, the presences of a British backed free Norway in the North keep many nationalistic sentiment in southern Norway, and a lot of the Reich resources in controlling the peoples.
After the fall of the Soviet Union in 1944, southern Norway was the focus of several meetings in Stockholm between Swedish, British, Free Norwegian and German diplomats. Germany would stop any repression in southern Norway allowing nationalistic separatist to either go to northern Norway or Sweden, and the free Norwegian government would stop supporting separatism by military means.
This was the first of several compromises that ended in 1950, when Free Norway resigned her alliance with the United Kingdom and the Reich de-occupied southern Norway. Both Norways were reunited after 10 years of separation.