Forever and a Day — Ashley Malkin

While on a mission for their pride of cougar shifters, Fergus, Tanner, and Nash Willis discover their mate, Sienna. Sienna has been held captive and tortured for centuries; freedom to her means only one thing--she's finally allowed to die. The brothers come to understand the horrors Sienna has had to endure, but they are unable to grant her wish for death. She's their heart now, and they'll die with her if that's what she chooses. Sienna is embraced by the pride in Pine Falls, their bonds of love and friendship paving the way for her to see the joy and love life has to offer. Once mated, however, Sienna is suddenly thrust back into the agony of her past when an old and powerful foe threatens to tear her away from her new mates. Sienna gains new strengths from her mates' love, but they still need the help of the entire pride to rescue Sienna and keep death from finally claiming her. Note: This book contains double penetration.