Why would ANY two rulers of neighboring territories become enemies?
Also, I know that Herod was a terribly jealous man and very insecure. Was he the Herod that murdered his wife and children, or was it his uncle (the Herod who had murdered the babies of Bethlehem)?
The Herod who murded his wife and three of his sons was Herod the Great.
Herod Antipas, who sent Christ back to Pilate, was one of his remaining sons. If he was insecure, I’m not surprised with a model like his father. I suppose they were both insecure, but Herod the Great would have been the insanely jealous one.
I think a Roman contemporary commented about Herod Antipas, “He has all his father’s vices, and none of his virtues”.
A link to Herod Antipas follows -
en.wikipedia.org/wiki/Herod_Antipas
As for Pilate and Herod becoming friends, I suppose there could be several reasons. Neither of them liked, or were liked by, the Jewish religious authorities. In fact they were both probably hated by the scribes and Pharisees, and I suspect they reciprocated.
By returning Christ to Pilate, Herod had effectively said to the Pharisees and Sadducees that Christ was their problem, not his. Pilate felt exactly the same way.
There’s an old political saying, “The enemy of my enemy is my friend”.
As to Christ being a “peace maker” in this context, I don’t think that is the reason. Both of these men served the devil pretty well, and the devil has the ability to make strange bedfellows when they serve his purpose. Stalin and Hitler were ideological opposites as far as politics was concerned, but Stalin trusted Hitler more than any other Western politician. They had quite a cosy trade arrangment, where Russian raw materials were sent to Germany in exchange for machinery - a form of barter so they didn’t have to use banks, and could avoid problems like borrowing with interest, and a drain on national funds.
Even when Hitler initially invaded Russia, Stalin still couldn’t believe it at first. They hadn’t exactly been friends, but where it suited them, they were prepared to work together since both Soviet Russia and Nazi Germany regarded most Western powers as their enemies.
Similar story, except here the focus of attention is God the Son.