It took time, but the Heartless were persistent. With only one goal that could exist in their minds for any length of time, there was no option but to keep trying until it reached the hearts it needed or it died trying. Which was why the Anti-Form didn't let up. It continued to claw at the door, aiming high where the desks weren't in the way.

But these doors were built to keep any patient in (and to keep monsters out), and for that reason its efforts were almost pointless. Its claws glanced off the door like they were bad of paper instead of something that was more like hardened rock.

The next idea it had was to try and ram the door open, and so it backed up to get a running start and then slammed itself against the door with all its weight.

The door barely budged.