The phrase "leave cold" refers to lack of emotional reaction or indifference to something. Its antonyms are the words 'capture,' 'enrapture,' 'fascinate,' 'excite,' 'thrill,' and 'engross.' These words all relate to the engrossment and engagement with something that sparks an intense emotional response. When something captures our attention, it usually evokes a positive reaction or feeling, unlike leaving us cold. In the context of relationships, saying which someone leaves us cold means that they do not excite or interest us. In contrast, people who fascinate or enthrall us usually generate a profound level of interest and attachment.