Just noticed this. The Spring and Autumn courts are quite prominent in my game, though currently I'm keeping them pretty mysterious.
I have the King of Autumn being the Reaper (aka Samhain, but Reaper is his most common name these days). He's a terrifying figure dressed all in black, resembling Reverend Kane from Poltergeist II. He is utterly without mercy, but also without cruelty. It is his job to end things and he does it. He is, however, pretty bad at political games and often leaves unintended loopholes in his edicts which his Prince exploits.
Jack is the Prince of Autumn. Which Jack? All of them. Jack Frost, Jack O'Lantern, Jack the Giant Killer, etc. He was once a mortal, but he tricked his way into power in the court when he trapped the Reaper King in a magical sack. He wanted immortality, and got it as a Sidhe. He also cannot be killed or significantly harmed by any forces of Autumn, including, unfortunately, the Reaper King, which makes his ambition to become Autumn King dangerous. He looks like a surprisingly ordinary young man dressed in slightly old-fashioned "country boy" clothes.
The Spring court hasn't been dealt with much, but they're currently courting (no pun intended) a PC to be the Knight of Spring. She also happens to be Jack's daughter, which would be a huge insult to to Autumn. Their representative is a certain Robert Goodman, who is a slightly sleazy but charming man in a suit who lives on deals and tricks. He's actually Puck, and the Prince of Spring. Naturally, Oberon is the King, though he has yet to appear "onscreen."
Cool story! Between you and Sanctaphrax's ideas i like how the other 2 courts can be shaped. Though i personally intend to make Samhain and the Reaper separate. I want to follow the heiarchy of the Winter and Summer Courts The Mother, The Queen and the Lady. (though it will be The Father, King and the Lord for Spring and Autumn)
Keeping with both ideas:
Autumn:
Lord: Jack the Pumpkin King: Granted he has "King" in his personal title, but he was elevated to Autumn Lord because he will be partially responsible for the restoration of the Autumn and Spring courts. Which results in freeing Samhain and Oberon From Mab's clutches.
King: Samhain:
Father: The Harvester (Reaper): While he does look like the classic Grim Reaper, i wanted him to represent the harvesting before possible death.
Spring:
Lord: Puck: As true to his nature he "tricked" Jack into helping him being back Spring as well as Autumn and was rewarded with the power of the Lord of the Spring Court.
King: Oberon
Father: This is where i am having difficulty filling this slot. Any and all suggestions would be very helpful.
Again My thanks to Sanctaphrax and FishStampede for the wonderful ideas!