The Lord's Strategy, the Beauty's Cunning Plan

She forms an alliance with him for reasons she can't reveal.

She helps him seize the throne, and he helps her destroy her enemy's kingdom.

Once it's over, not a trace remains; their names never make it into the history books!

P.S.

1. The heroine is strong, and the hero is even stronger.

2. Early on, she battles the Crown Prince and cuts down his supporters; in the middle, they fall in love and make everyone jealous; in the end, they fight for the world and uncover the truth.

3. Everyone, I love writing fight scenes. The kind where they start throwing punches at the slightest disagreement...

4. This isn't a feel-good power fantasy.