The Unseelie Wish by Kathryn Ann Kingsley

In a world where fae magic thrives and wishes hold unimaginable power, Alex faces a choice. The rules are set by Izael, the beguiling Unseelie Duke, who presents her with a simple game—surrender her soul with a wish within seven days or prove her indifference and gain freedom from his enchanting clutches.
As the sands of time slip away, the stakes skyrocket. The sinister Unseelie King, Valroy, emerges with nefarious intentions, seeking to exploit Alex’s wish to unravel the very treaty that safeguards Earth from the dark forces of the Unseelie fae. To make matters worse, newfound magical abilities transform Alex into a potential weapon—one capable of unleashing chaos upon Earth and Tir n’Aill.
With each passing moment, Izael’s allure tightens its grip, drawing Alex into a web of temptation. His teal eyes flicker with an otherworldly flame, beckoning her to succumb to desires that pulse beneath the surface. But can she bear the cost of surrendering to the intoxicating charms of the snake?