Even if monsters world is unpredictable, some aspects work more or less the same than in natural world.
Big monster eat little monster seems to be an unmodifiable law in most of cases.
Alien-like green monster with one eye, antennae, pointy ears and sharp teeth feeling stared at when chewing a little monster. The big monster reacts angrily while the lizard-like blue one complains in pain.
(Or a similar design)