The Blood Bond

When Evelyn Mason meets Klaus Mikaelson it's like a new world is introduced to her. Vampires she was used to. Psychos? She lived with one. But she never expected someone to be so in love with her that they try to make sure she isn't the one that gets hurt. Evelyn mason is so used to being the mortar, being the one that was in danger, that Klaus's kindness is something she is skeptical of.
But she doesn't know why he's so protective of her. Klaus's family were one of the last recipients of an ancient magic long since destroyed. Most people would call it soulmates. Witches call it "The Blood Bond"