Circle trilogy (Nora Roberts)

"In the last days of high summer, with lightning striking blue in a black sky, the sorcerer stood on a high cliff overlooking the raging sea ... Belting out his grief into the storm, Hoyt Mac Cionaoith rails against the evil that has torn his twin brother from their family's embrace. Her name is Lilith. Existing for over a thousand years, she has lured countless men to an immortal doom with her soul-stealing kiss. But now, this woman known as vampire...

Her face, so pale when she'd removed her cloak, had bloomed when her hand had taken the sword. Her eyes, so heavy, so somber, had gone as brilliant as the blade. And had simply sliced through him, keen as a sword, when they'd met his... In the kingdom of Geall, the scholarly Moira has taken up the sword of her people. Now, as queen, she must prepare her subjects for the greatest battle they will ever fight--against an enemy more vicious than any they...