Mallory Hemlock and Brother Hellion from Spire: The City Must Fall
She is a lajhan (priestess) of Our Glorious Lady.
He is the head of the Church of the Gun.
When they first met, Mallory was full of resentment because Brother Hellion charmed her friends with his preachings. She devoted her heart and soul to Our Glorious Lady, so the mere thought of turning to another religion filled her with disgust.
During a religious ceremony in the Church of the Gun, Mallory showed disrespect, and Brother Hellion noticed it. He put a metal hand on her shoulder and squeezed it a bit. Then he whispered some words that made her furious. However, the friends of Mallory quickly grabbed her and took her away before she started a fight.
Their relationship was chaotic and hateful for a long period of time. She was spying against him, he tried to kill her… But then something has changed.