ooh, wait, wait- Hear me out
living castle + killer w/ vision issues
Killer is blurry eyed at the best times and stark blind at the worst, so I think the castle will guide someone to him to help him get where he needs, or it'll light up the sconces on Killer's path brighter, so he can follow the lights. Regardless of how blurry things are or how bad the tunnel vision is, he can see the lights. Maybe as he's walking along the wall, his hand bumps into something, and he finds a railing. He's never seen railing anywhere but on the stairs, but he trusts the castle to get him where he needs to go when he's like this; He doesn't really have any other choice.
The castle may be a little mean and a lot mischievous, but it looks after its silly inhabitants when they're struggling.
