" Sasha had been a rogue cat wandering the forest, until she had come to RiverClan with her kits and settled briefly there. She might have visited ShadowClan when Tigerstar was leader. It was possible. . . . Leafpaw froze. She realized which cat Hawkfrost resembled so strongly. Brambleclaw! And every cat knew who Brambleclaw’s father was. Could it be possible that Tigerstar was Hawkfrost’s and Mothwing’s father as well? If he was, that would make Hawkfrost and Brambleclaw half brothers. "

― Erin Hunter , Moonrise (Warriors: The New Prophecy, #2)