Wolf Castle by Heather Walker

While Callum and Jamie Cameron leave Urlu to visit their remaining family and Clan, they encounter their near neighbors, Clan McLean.
Dashing young Clan Chief Lachlan McLean welcomes the brothers as long-lost friends, but the reunion quickly turns sour when Callum discovers Sadie Cole—one of the time-traveling friends of the women back in Urlu—among the McLeans.
Although Lachlan has his heart set on Sadie, Callum cannot fight his growing feelings for her. He finds himself compelled to keep his attraction toward her a secret to maintain the peace between the two Clans.
But an ongoing war between the McLeans and a vampire scourge forces the wayward hearts together, tearing the peace apart.
Can Callum and Sadie balance their love while catastrophe breaks out around them?
Or will their forbidden love bring the Phoenix Throne and the Kingdom of the Urlus crashing down?