Quite frankly, Deadman doesn't know whether removing the hats from any of the civilians might give them some kind of psychic or even physical shock. With one of Hatter's obvious lumbering thugs he was willing to take the risk, but he's not going to start lobotomising innocent kids just to break them from Tetch's control.

It had occurred to Deadman to invade the Mad Hatter's body, but having tried that with the Joker and experiencing a trauma nearly as bad as being shot off a trapeze, he's not so keen on possessing other Arkham inmates.

So he tries something a little different, and makes Candle-ends take a running dive at the Mad Hatter in his weird high chair, hopefully dislodging the criminal's hat at the same time.