Before Root & Ruin - Rose Ravenscroft

The grove was hungry.

Aisling felt it in the soles of her bare feet - a slow pulse rising through damp earth and tangled root, a heartbeat not her own. She had served the Bloodroot Grove since girlhood, the way her mother had before her, and her mother before that. She knew what the land wanted. She knew what it had already taken. And when the grove whispered completion and showed her a grey-eyed stranger at its border, she knew something old and terrible was about to be asked of her.

Cael of Ashvale was meant to be his father's weapon - a hostage in name, a spy in fact, sent north under a peace-truce to find how the sacred forest his clan had warred against for three generations could finally be broken. He was not meant to fall in love with its keeper. He was not meant to hear the earth speak his name. He was not meant to choose her people over his own.

Their love is forbidden in every language they share. Their clans will never forgive it. The grove does not care. It has waited longer than memory for blood freely given - a union to satisfy a hunger older than the first oath ever sworn. What Aisling and Cael offer will end a war. What it costs will bind every descendant who follows them to a grove that will never stop asking, an oath they never chose, and a love that rooted itself into the bones of the world.

This is the story that started the Bloodroot legend.
The land remembers. The oaths endure.