I had to look that up and found this nice little video (with a Jethro Tull soundtrack to boot)
Quick Summary, these 2 kings are twins and they constantly pitted against one another.
But there is something about the story that is so counter-intuitive for me, and I wonder if anyone can explain.
It says that
So at midsummer, the Holly King wins, and at midwinter, Yule, the Oak king wins.The Golden Oak King, who is the Light Twin, rules from midwinter to midsummer.
The Darksome Holly King rules the dark half of the year from midsummer to mid winter.
This seems completely backwards to me. Surely oak trees are at their height in Summer and Holly at winter when the Oak trees are dormant.
Does anyone, maybe with some knowledge of the Druids, have any clue, because according to the story, the Holly King is dominant right now.
Or am I, as Jethro Tull once sang, thick as brick?