As a race, the pyreen were not unified as a block, for each nearly immortal individual preferred doing its own thing; that is, until Alar Ch’Aranol succeeded in unifying a large number under the banner of Peace-Bringers, in opposition to their brother the Warbringer. Many to this day still do not count themselves as Peace-Bringers, carrying on their own private agendas.
What other group of pyreen could there be?
The pyreen remind me of the Heralds on Roshar, from Brandon Sanderson’s works.
I think there may be a small group that aligned with Rajaat, perhaps something along the line of the Cult of Storms/Peacekeepers split in the elven court in Age of Wonders 1. A group that from whatever origin had their leader murdered by a group of rebirth races, or perhaps several leaders over a period, and decided to join the warbringer to end the chaotic disharmony of the humanoid races.
As for other groups, perhaps something along the line of a group of Pyreen that hid in the southern arctic of Athas, and now are slowly growing the southern sea that is visible in the world map
A small number of pyreen could have sided with Rajaat, but then been killed (by Rajaat himself?) and subsequently raised. Undead (former) pyreen? Bound to assist him in his research, perhaps?
Right off the rip, I could see them trying to keep certain areas safe, like visiting certain areas free of defiling. If you are looking for specifics, I would point towards areas where the Unseen War might spill over, or areas of high tensions between Monarchs. The entire intention there would work like NPC quest givers, gently pointing people in the right direction, hoping to deescalate conflicts and prevent planar imbalances from becoming worse.
One could be interested in the Silt Sea, quietly trying to prevent further incursions and subvert Silt Priest activities. Chain of quests escalate to situations where the party might have to deal with an elemental monolith or something like that (or a Primal Silt Elemental if its an epic game).
One could be invested in the Dead Lands, aware of the slowly growing silt but unsure of what to do. They start investing in adventurers, looking into the spirits of the land - and learning of the curse of undeath that wrecks the area.
An interesting thread. As I believe Pennarin knows, I generally reject the 2nd Box notion that Rajaat was a pyreen. Denning was quite clear that Rajaat was human. I believe this is important, because that makes Rajaat’s beliefs tied closely to we human players. The naturally nearly immortal and very powerful pyreen are very difficult for us to imagine and understand. Denning’s intent was to square the Cleansing Wars as a human cataclysm, and not one that is led by an unnecessarily alien and esoteric entity such as a pyreen-Rajaat.
That said, pyreen to me are rather clearly descendants of the leading Nature-Masters who reversed the Brown Tide from the Pristine Tower. They too transformed when they descended from the Crystal Cupola, but instead of into a particular new race, they transformed into an amalgam of the humanoid races to be. Seemingly there were enough of them so that they might reproduce, and more than this pass on their powers to their descendants.
I am fascinated by the pyreen in part because it seems to me the original Nature-Masters imbued themselves with profound power from the Pristine Tower. Instead of using sorcery, they used their powers over Nature (science?), and the Dark Lens mounted high upon the Steeple of Crystals imbued them with profound clerical and even psionic abilities. This may have made them the first psionicists on Athas. It would also explain how the Elemental Planes are tied to the very cores of their bodies, as even their descendants possess their powers. This is similar to, yet different from, the sorcerous use of the Pristine Tower when the future Champions were imbued with profound elemental power.
I would wonder, now millennia in the future, how much of this primordial history the pyreen would know. What more might they know, or be capable of achieving? These relics of the deep history of Athas might be tied closely to the fate of that world, and they may know much about how to repossess from Rajaat the World Spirit of Athas, and use it to heal and rejuvenate the world.
In any more realistic DS campaign, an explanation for what the pyreen are doing, and what they are not doing, is important. These are challenging explanations, and as a consequence I am very cautious in their use in any DS campaign.