When the zoo was abandoned, many of the animals died, for lack of care.
Not the monkeys! They thrived, using their above-average intelligence (for animals) to mimic the humans who once took care of them.
They multiplied. There was monkey shit everywhere.
A sea of monkeys.
Monkey sea, monkey doo-doo.
Vampires and zombies emerged at the same time.
Nobody knows why.
They fought for their main resource: live humans.
Eventually, none were left. The zombies and vampires stopped fighting, with nothing left to fight for.
Gradually, with no “food” left, both groups faded away.
Guess that’s a happy ending, right?
A faraway future:
“Who are you?”
“I’m your guardian angel.”
“Boy are you wasting your time, then.”
“Why? You think you don’t deserve me?”
“You already have a guardian angel?”
“You don’t believe in angels?”
“I’m an angel too. The humans are gone.”