Instead of coming back, Light sends movers.
It happened while you were gone at school, and now it's nothing but a bare, four-walled space. His bed is gone. His bookshelves and his books, his TV and his computer, every single thing; and the room looks like it belongs in a house someone is moving into, or out of.
That's when you really know he's not coming back.
You sink down to your knees just inside the doorway and feel sudden tears coming to your eyes, and for the first time in your life you hate your brother. It's just as much your father's fault—this stupid argument—and so you hate him, too. It doesn't make you feel any better to hate them, just vaguely ill, and you're pressing your hand to your mouth to stifle the sounds. You don't want to cause a fuss, or worry mom. She has enough to worry about. You just didn't know everything that belonged to Light would vanish, like the world was trying to erase his existence entirely. If you'd known, you'd have taken something… hidden it. If you'd known, you wouldn't have let him leave without saying goodbye.
.
.
.