When trapped and surrounded by blank white walls for so long, an innate need for something, literally anything out of the ordinary. Change, hope, escape, solace, call it what you want, since what it was was undefined. There was just that tiny thing, where it was easier to delude yourself and paint the bleak walls with sunshine rather than face the peeling plaster. .
When he discovered the existence of a child in Arkham, he assumed their mental state would be dire. It took weeks of forms and checks before he could actually arrange a visit with you, all the while he couldn't help but only hope for the best - even though his expectations were below low. In the best case scenario, you were just another nut-job with questionable decision making skills, but there were so many 'worst case scenarios' that he was almost waiting in bated breath in the lead up to the visit. Finally, as the hour struck, his forefinger tapped against his leg as he waited outside the door to your room, waiting for it to unlock.