Bruce had no other choice, he had already lost you to the joker once. So while you were grabbing your costume out of one of the glass display cases in the cave Bruce pushed you into it and locked you in. He remained stoic as you pounded desperately on the glass, muffled screams falling on deaf ears. You continued to throw yourself against the glass, but of course every failsafe known to man was considered when Bruce had created the cave and everything in it.

Bruce said nothing except,"This is for your own good, I promise I won't be long. Just...stay there, Please."He then turned to walk away, already climbing into the batmobile and driving off, leaving behind muffled screams in his wake.