Batman AU where everything is the same, except Kirk Langstrom doesn’t have the villain ball and experiments with fruit bat DNA instead of vampire bat. So he essentially looks like a ten-foot tall version of this.
He’s the scourge of farmer’s markets and juice bars around Gotham every time he transforms. The Bat-kids fight over who gets to go wrangle him each time, and then they ride him back to the Bat-cave where Bruce works on synthesizing an antidote. Cass and Steph pet him and put bows in his fur. Damian tries to turn him into a battle-bat, but it doesn’t go well and he always just winds up flying away and eating Alfred’s imported pears.
When he’s de-transformed, he’s always very confused and wonders why he always winds up with strange colorful things in his hair.