Legend (Real #6) by Katy Evans

Maverick “the Avenger” Cage wants to rise to the top and become a legend in the ring. Though he keeps his identity well guarded, he's known on the fighting circuit as the new kid with a chip on his shoulder and a tattoo on his back that marks him as trouble. He's got a personal score to settle with the Underground's one and only Remington "Riptide" Tate.

As Mav trains, he meets a young girl—the only other new person in the town--and sparks fly. When things get heated between them, he finds out she's none other than Reese Dumas, the cousin of Remington Tate’s wife. A girl who's supposed to root against him and a girl he's supposed to stay away from.