Season 1

Charlotte moves to Clamburg from Vermont. Vendetta, a mysterious evil girl, terrorizes the city. Charlotte is unaware of evilness, and thinks Vendetta is her best friend.

For Show and Tell, Vendetta releases a monkey fiend, that eats Marion's unicorn toy and throws away Marvin's bananas, but things go awry when Charlotte introduces Buttons, her hamster, to the Giant Kitty.

Charlotte notices that there are no vegetables in the school menu, after Vendetta hears about that, she decides to make some screamy vegetables fiends.

After Charlotte bothers Vendetta too much, so she decides to make her a snipping fiend, but the plan backfires when Charlotte befriends the fiend with love and renames him Buttons 2.

It's Halloween and Charlotte dresses up as Vendetta and Vendetta gets the plan to get rid of her by making a fiend that only eats and drinks blood if he eats Charlotte.

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Vendetta makes a slug that shrinks whoever touches it, but when Vendetta and Grudge accidentally get small they make growing squid.

Charlotte keeps bugging Vendetta about her birthday. So, Vendetta makes a birthday party with many hazardous things like balloons that tie you very tight, a man-eating birthday hat, a taunting present wanting her liver, and an exploding strawberry birthday cake.

When Mr. Milk is sick, Mrs. Minty, the substitute teacher, is trying to teach the class.

Charlotte shows Vendetta her canary and Vendetta lies by saying she is going to Florida so Charlotte can care for her fiends.