Who is most closely related to Sir Percy, Florence’s cat who in Chapter 7, went primal, and ate the fish and a bird?

Randy relates this to the now common denominator of existence, survival of the fittest:

"The strong survive. The frail die. The exotic fish die because the aquarium isn’t heated. The common guppy lives. So does the tough catfish. The house cat turns hunter and eats the pet bird. If he didn’t, he’d starve. That’s the way it is and that’s the way it’s going to be."