A Tongue so Sweet and Deadly (The Compelling Fates Saga) by Sophia St. Germain

For readers of Callie Hart, Sarah J. Maas, and Sarah A. Parker, this first in a slow burn, enemies-to-lovers, love triangle romantasy saga dazzles with political intrigue, compulsion magic, and found family, as a half-Fae blood sworn to the Fae king and drawn to a brooding human regent is forced to spy in human elections to win her freedom—but starts to realize it might come at the cost of an entire nation.

Half-Fae Elessia could have had everything. Literally.

Since her magic allows her to compel anyone to do her bidding by merely looking into their eyes, the world was at her feet. But after a tragic accident, she is thrown into the Fae king's dungeons and forced to swear a blood oath to him, binding her to his service.

Five years later, she's living amongst humans in Ellow and has created a life for herself—as much as she can with the king's promise to call in his debt looming over her.

When he finally comes to collect, she is made to infiltrate the human elections to determine whether the current regent is involved in the strange things happening in the land of Fae.
With the promise of freedom from the king's claws, Elessia is determined to see it through. Liberty is within reach as long as she can keep the lethal Fae guard watching over her from eliminating her before she unearths the information the king seeks.

But as she grows closer to the brooding human regent and secrets begin to unravel, Elessia realizes greater forces may be at play.

And she might stand before the choice between her own freedom and that of a nation.