Revenge. That's what motivates main character, Wu Zetian, in the novel Iron Widow by Xiran Jay Zhao. Zetian's revenge plot begins as a way to avenge her sister who died at the hands of the military but continues to grow the more corruption she uncovers.
Zhao's novel is a reimagining of China's past, set in a future world where humanity finds itself at war with an alien species known as Hunduns. Humanity fights back by turning Hundun husks into mecha creations called Chrysalises. Men pilot the mechas by using energy siphoned off their female co-pilots, who usually cannot survive the experience. Zetian finds herself paired with the strongest pilot in modern times, former death-row inmate Li Shimin.
Finding themselves surprisingly compatible, Zetian and Shimin journey down a path to dismantle the whole system. They're helped along the way by Gao Yizhi, a rich son of society's elite. Are these three strong enough to protect humanity while taking out the corrupt? After all, the triangle is the strongest shape.
10/10 Chrysalises. Highly recommend!