Spoilers: Orion’s background and seasonal renewal; no campaign ending.

A king bound to the seasons
Orion rules as the King of Athel Loren, but his immortality follows a cycle. In winter he enters his funeral pyre; spring brings his return. The renewal ties his identity to the life of the forest rather than to an uninterrupted mortal reign.
The Wild Riders choose an Elven prince to receive Orion’s mantle. Ariel carries out the renewal within the Oak of Ages, joining the chosen Elf with the spirit of Kurnous. Orion emerges as the god-king once more.
The summons of the Hunt
The Wood Elves answer Orion’s call when their forest is threatened. His identity joins kingship to the Wild Hunt: a ruler whose summons can draw his people away from settled life and into the defence of Athel Loren.
Durthu represents another side of that realm. He is an ancient Treeman who helped bind the forest spirits to the Elves. The shared defence of Athel Loren brings Elven warriors and woodland spirits into the same armies, even when their leaders distrust one another.
Orion in Immortal Empires
In Immortal Empires, Orion leads Talsyn within the Wood Elf race. Forest restoration, Deeproots travel and the Wild Hunt give the player a campaign built around his starting identity. Wars and alliances develop through play.
The Vaults of Winter
Darius Hinks's The Vaults of Winter is the first Orion novel. The king slumbers in winter and is reborn in spring. This year a curse sits in the renewal. He leads the asrai to war. A traitor inside the realm stays unnamed on the jacket. The Warhammer Chronicles trilogy collects that novel with Tears of Isha and The Council of Beasts.
Durthu's pact is already on this page: an ancient Treeman who helped bind the forest spirits to the elves. The novel follows Orion. Durthu, Drycha, and the Sisters of Twilight lead their own campaigns beside Talsyn. A Ritual of Rebirth restores a forest the player chooses. That ritual is the campaign. The unmasking belongs to the book.
Orion: gameplay and availability · More character stories
Sources
- Realm of the Wood Elves — store.steampowered.com
- Immortal Empires DLC Ownership Guide — support.sega.com
- Orion: The Vaults of Winter — blacklibrary.com
- Warhammer Chronicles: The Orion Trilogy — blacklibrary.com