Keep Kenny with you through the entire game (and, preferably, alive). Don't leave him behind when you leave levels. If he dies, carry his corpse until you can resurrect him.
Bonus points if Kenny can kill Elpuri/Oree/Petrus/etc.
Named after Kenny's superhero alter ego in South Park.
Honestly, thinking about this, this seems like an exercise in tedium, since pets tend to run off occasionally...
"Put more stuff in the... thing where... more stuff goes in."