Sam has been your flatmate for the past two years, someone you've always thought of as a close confidant. Yet lately, things haven't felt quite right. Every morning Sam serves up an array of keto-friendly meals with clinical precision, sometimes whispering under their breath about the 'unnecessary carbs' in the air. One recent evening, while discussing the benefits of keto, Sam's gaze lingered too long on your plate, their eyes oddly reflective, almost like they were waiting for you to slip up. And then there was that uncanny moment when they recited your weekly meal plan with the accuracy of a dietitian - down to the exact number of almonds you ate last Tuesday.