Blood Thirsty - Dead Man's Hand Series, #1

To stop a ritual for power, bloodlines must be drawn in the sand. A war that has raged for a millenia may come to a close as werewolf alpha Lukis attempts a ritual that will give him unspeakable power and incite a cataclysmic event that will affect the whole world. He is willing to sacrifice everything for it, even his own offspring. Leading a coven of vampires, Ace aims to stop him, but she may be thwarted by her own past and a love triangle she wanted no part in. Her sire and former lover Nero has returned to London after decades of abandonment, longing to rekindle the flame between them.
But Ace is resolute-the mission comes first, even if the pull toward Nero is stronger than she'd like to admit. Six, the progeny she sired in secret, arrives soon after asking for help, and her acute instability threatens to upend the mission and Ace's reunion with her sire. Blood is thicker than water, but family can be a real pain in the fangs.