The Hating Game by Sally Thorne
in The Hating Game, Lucy is the executive assistant to the CEO of a publishing company. When her company merges with another, the heads of both companies are kept on as co-CEOs, and Lucy is forced to start sharing an office with her counterpart Joshua. In contrast to cheerful, quirky, approachable Lucy, Joshua is an intimidating and seemingly humorless workaholic. They hate each other instantly, and before long, they’ve made a game out of trying to outdo and annoy each other.