It's when he's walking by, when his wrist accidentally brushes hers. It's the look they exchange afterward. It's the way he's careful, careful not to touch her too much.
It could start with this. It could start with anything.
They know this, and they're careful for it. It's hard, sometimes. They're playing with insanity and it's hard not to give in.
It's hard, to repeat these things. To have a reminder. There is a pile of sticks between them waiting to start a fire, and it goes untouched but not ignored.
Maybe it's about forbiddance. Or maybe, it's about them.