Fruit-Bat-Man is a limited-time premium costume for Mr. Burns, rather than a new character in the game. As with most costumes, you’ll need to have Burns free to be able to use it.

Once he’s free, open up his task menu – you’ll now see a choice of costumes. Swipe to the Fruit-Bat-Man costume – Burns will put it on and his tasks will be available (and his quest should begin).

If you’re not sure where to look to get Burns to put on his Fruit-Bat-Man costume, here’s a screenshot:

I can’t wait to make him fly!