When walking the halls of the Intensive Treatment building in Arkham Asylum Island, in the corner of your eye you spot a figure, with needles on their hands, that they then stab into your back before you can react.

Scarecrow: Shh-Shh, shh. You're in my world now... heh-heh, eh...

You start to hallucinate your biggest fears, and Scarecrow walks in front of you.

Scarecrow: What are you afraid of?