novel spoilers for this one ofc
but its revealed like i think way closer to the ending that chripy was in a bit of a dilemma. He decided to hold onto the rat so that Soul wouldn't have tp get close to it while rescuing everyone, and he hid it from soul's eyes so that soul wouldnt look at other rats
basically big idiot was jealous and didnt wanna take chances on soul liking other rats
also they dont show it here ig but in the book after chirpy runs out after the argument, the rat they rescued makes fun of him for getting dumped. they literally dont fw each other

Yeah this ruined it for me