How was Fridlevus II related to Halfdan?
Fridlevus II Fridleif (Ynglinga saga) was a son of Fróði of the Skjöldung (Scylding) lineage. In that work he was the brother of Halfdan and the father of Áli the Strong.
Christian, Prince-Elect of Denmark Christian (10 April 16032 June 1647) was Prince-Elect of Denmark since 1610 and Heir Apparent to the Throne of the Kingdom of Norway since 1603. Dying in 1647, he was succeeded by his younger brother, Prince Frederik.