The first day on the job is kind of like the beginning of a new school year. Yes, you want to do well, but let’s be honest: the only thing running through your mind as you wade through the sea of unfamiliar faces is, “Will anyone like me?” And then, blessedly, as you settle into your new space, one of your co-workers stops by your office to introduce herself with a warm smile and an invitation to lunch. You feel relieved, like you’ve found a new friend. The lovefest continues until a few months later, when you’re both up for the same project or promotion and your “friend” suddenly becomes your worst enemy, undermining you at every turn. Yup, you’ve got a case of the “frenemies,” which you might not even realize, since she’s keeping her chummy charade up to your face. So pull the knife out of your back and know that you’re not alone. These women also have frenemy scars. Read on.