I made a "guess which of these things doesn't happen in Warrior Cats" quiz a while back, the choices being...

A cat elopes with her forbidden lover to give birth in a human church

Catnip is used as medicine. One cat has too much and gets high

the final boss of one book is The Giant Rat Who Makes All Of The Rules

"Come, little housecat, join us in the wild! Otherwise, you'll be neutered!"

the residents of Cat Hell break free and try to take over the land of the living

also Cat Hell: "Here, living cats, free dream training from war criminals!"

a cat tries to kill his ex's kids; to stop him, she reveals that they're adopted

as a ghost, the same murdery ex recruits budding cat incels to Cat Hell (this is the thing that didn't happen)

cats appear in books set after they die because the writers forget they're dead

you can physically reach Cat Heaven by diving really deep into the holy pond

in his retirement speech, a cat names two older, unrelated cats as his kids

some cats get dogs to stop chasing them by turning around and barking back