J. R. Ward 
Lover Enshrined [EPUB ebook] 
Number 6 in series

And now, a dutiful twin must choose between two lives . . .Phury has sacrificed himself for the good of the race, becoming the male responsible for keeping the Black Dagger Brotherhood’s bloodlines alive — he is to father the sons and daughters who will ensure that the traditions of the race survive and that there are warriors to fight those who want all vampires extinguished. As his first mate, the Chosen Cormia wants to win not only his body but his heart for herself — she sees the emotionally scarred male behind all his noble responsibility. But as the war with the Lessening Society grows more grim, Phury must decide between duty and love.