I was going back and forth on it for a while, but I've decided in very broad terms there will be some sort of Alliance-kaldorei conflict after secession (like, decades after). In-universe it's gonna SUCK for everyone involved but I think it'll be fun to explore.

Shortly after secession the kaldorei and Horde reached an agreement not to intrude on each other's land, but a similar agreement was never made with the Alliance. And after some internal conflict of its own, the Alliance is eager to expand its influence on Kalimdor. The draenei still exist as an Alliance foothold on the continent, but despite an overall friendly relationship with the kaldorei, the draenei were still not permitted to move troops through their lands. The Alliance would have to get creative.

It starts with land surveyors "accidentally" wandering inside Kal'thalas' borders (hc name for the kaldorei nation), then hunters, miners, loggers, and the sort following suit. Diplomats from both sides try to find a compromise, of course, but soon it's soldiers and mercenaries, and skirmishes break out here and there. It's when an Alliance surveyor finds an untapped and extensive source of gold that a true effort to settle inside Kal'thalas is made. Soldiers, miners, civilians... it's close enough to the border, surely the elves will make another exception?

That settlement is razed to the ground in a single night. The ones responsible are never identified.

The war that follows is one fought between former allies, each with extensive knowledge of the other's capabilities... or so they each believe. It will not be won through honorable combat. And having only just regained proper control of their lands, the kaldorei will hold nothing back.

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Though Tarinne had long left her days as a Sentinel behind, her sense of duty to her people and her lingering hatred of the Alliance will come to the forefront. For her, this will have been a long time coming.