At lunch, there's a girl called Lily who often ends up sitting alone. It's not that anyone's banned her from sitting with people. It's subtler. When she approaches a table, there's a small shuffle — bags moved onto seats, a slightly-too-long pause — and somehow there's never quite room. Nobody says "go away." They just don't make space. A kid watching from another table can see exactly what's happening. There's a free seat next to them. Lily is scanning the room with that careful, casual look people do when they're trying not to look like they have nowhere to sit.