Maybe the cat is Gasprrrd.
“Ah, yes, it all makes sense, doesn’t it? We’re dealing with a Dickensian scholar here, no doubt about it. These layers of symbolism cannot be ignored. The use of dark versus light. The little bird clearly representing Manette’s imprisonment. The consumption of that small winged creature as a nod to the real torture of de la Barre, or perhaps on a broader level, all of the revolutionaries in Book the First. Then there's the cage. Is it Bastille? You’d like to think so, but I don’t think it’d be so obvious. No, I submit the cage is, in fact, the guillotine. And then, of course, the mouse. THE mouse. I know you’re thinking what I’m thinking: It’s gotta be Barsad. A spy. Selfish. Slippery.”
“Wow. So, uh, what about the cat?”
“The cat, you know. What’s it mean?”
“It’s just a cute cat. Gah, talk about overanalyzing.”