“A kiss. One-point-three seconds--and gone. He touched his metal mouth even though he could not feel--neither physical touch nor emotional. Ana had never kissed him on the mouth before. One the cheek, yes, when she'd drunk too much of Wick's Cercian ale. But never on the mouth. Her words echoed through his processors like a virus. I'll always come back for you. I promise on iron and stars. It was more than a promise--it was an oath. Unbreakable. Strong like iron and steady like stars. It was said that such promises could never be broken; the Goddess would not allow it. The probability of a supernatural binding was less than one percent, but the vow stuck with him all the same. Because Ana had never promised on iron and stars before.”
Book:Heart of Iron