This Ratman was one of Noah Goring's experiments.
Day 3[]
With Zac West he came to Ghirardelli Square and both attacked Noah Goring. Meanwhile Goring's ally was attacked by another rat on the rooftop. Goring put up a fierce fight and even severed one of the rat's Paws, but ultimately Zac dragged him back to his lair at the Wax Museum.
The Ratman remained hidden in the alley and attacks the Manhunter if he attempts to enter it. The Manhunter took his paw and took it to the Shop.