Heavenbreaker

The illegitimate daughter of a commoner and a duke, Synali von Hauteclare, survives an attack by an assassin hired by her father and plans her revenge by riding and fighting on a giant robot.
In a massive space station that houses the last of humanity, the king rules. Nobles dance. Commoners starve. And when they aren't starving, they watch the riding tournaments between the giant robots called "steeds"--once used in the war against the enemy, now repurposed for honorable lance-to-lance high-speed combat with a gravity generator. Only nobles may have the honor of riding. Only nobles may have the glory. Only nobles have the blood. In Synali von Hauteclare's world, she's a bastard; her mother a commoner, her father a duke. And she's just killed him. But he killed first. Seven people in House Hauteclare helped her father hire an assassin to kill her and her mother. Synali survived. Her mother did not. And now Synali will do anything to make them pay, even ally with a noble, her sworn enemy. Now she's made a deal: for every win she scores in the upcoming Supernova Cup, this enigmatic nobleman will kill one of the seven. She's never ridden, and the steed her new ally gives her--Heavenbreaker--sings strange lullabies in its hangar. And, increasingly, in her mind. With her half sibling, Mirele von Hauteclare on her trail, and hotshot pilot Rax who's trying to get in her bed, Synali has her hands full. But blood is all that matters. And she will ensure they see much of it.