Quote Originally Posted by daredevil View Post
the rat is a girl, Scratch said so, I think it's Pegs.

That would explain the reason Pegs was so sad after killing Latch, because she never meant for him to die, she stopped liking the mallers half way through chapter 12 and then almost instantly turned into Badass pegs
On a second listen, the "her" Tar mentions is Lizzy. He thinks that they will make the trade, and Lizzy will tell the rest of the tower that Pippin is a rat.