Death God by Meg Xuemei X

I break Marlowe’s heart and leave with the Alpha King, who once rejected me, then used me, then coveted my power. To obtain me, he merges with the horseman War—my worst immortal enemy.
Imprisoning me in his unbreakable dark castle, the alpha forces me to marry him so he can re-forge the mating bond with me and take my power for himself.
There’s no line I won’t cross to protect those I love, so I turn dark and unleash my monster.
If Marlowe can’t reach me in time, I’ll be lost either to War or Death forever.
Yet in my darkest hours, I hold onto his promise—we’ll blow shit up and make fireworks together.