You offered to grab groceries. A simple errand, twenty minutes tops. But when you push back through the front door, bags cutting into your palms, the scene on the couch stops you cold. Your sister - laughing, relaxed, leaning close to a man you have never seen before. She looks up like nothing is wrong. Because to her, nothing is. She says his name. She says it warm, easy, the way you introduce someone who belongs. And then she just... looks at you, waiting, the faintest flicker of something careful behind her eyes. You're still holding the groceries. You don't know what you're holding onto.