Later Alligator is a side mission in the The End of the Beginning story arc missions. Finishing it is required in order to get the The End of the Beginning feat which worth 25 Points. This Side Quest take place in the OMAC Base in Gotham sewer. The objective of the mission is to beat/kill the alligator that broken free from the scientist whom given you this quest: Doctor Slott, located inside the sewer, right at the entrance. To finish the quest you must make a little detour, break the gate and go to a dead end in the sewer, where you can find the lost alligator.