Cherokee Warriors: The Loner by Genell Dellin

Black Fox is a Cherokee Lighthorseman, a lawman who believes that the White man's law is the only way his people can hold control of the Nation. He is on the hunt for The Cat, an outlaw who has been stealing goods to deliver to poor families and allegedly killed a US Marshall in the process. After a robbery and subsequent shoot out in town, Black Fox spots a young boy running from the scene and follows him, sure he is The Cat. But to his surprise, the boy turns out to be a girl!

Cathleen O'Sullivan has no need for the law, especially when they refused to prosecute the man who destroyed her family. Now disguised as The Cat, she steals goods from her enemy to help the poor, and if it brings havoc to him and his bootlegging partners, then all the better. Then during a shootout, she is wounded, and captured by Black Fox. This ruggedly handsome lawman is not at all what she expected, especially when he cares for her wounds and protects her from her enemies instead of hauling her off to jail. She insists she's being framed for murder, and though Black Fox knows he should not be seduced by this spunky slip of a girl who has no respect for the law, he's torn between loving her and arresting her.