During the first four seasons, she was a cynical, yet charming character. But during the last two seasons, a more malicious side of her personality is shown.
Why She Was (Intentionally?) Even More Evil
Note: This only applies to her character as depicted in seasons 5 and 6 of The Grim Adventures of Billy & Mandy and the crossover special The Grim Adventures of the KND, as she was flanderized.
- Similar in vein to Ren Hoek's infamous Adult Party Cartoon flanderization, her cynical attitude has gone from being passable and generally tolerable to intolerable.
- Unlike her personality from the first four seasons, she is much meaner and has done much more evil acts than she ever did. She was much more laidback and calmer in the first four seasons, but here, her temper is much shorter and she beats up Grim, Billy, and Irwin just for fun, making her come off as sadistic. Even her own parents start dreading her for this reason.
- Much like Billy, she has become a huge bully towards Grim.
- She doesn't seem to care about Grim and Billy anymore, and instead only cares about herself.
- She usually betrays her friends.
- She also seems to do stuff that is just as dumb as Billy would do.
- With that said from, much like Shnookums, she is so delusional that she never seems to realize how she can be just as dumb as Billy is. This is because she's always condescending, sarcastic, and snobbish about Billy's unintelligent nature when Mandy can have her moments with being just as clumsy, hare-brained, and imbecilic.
- Hypocrisy: During these seasons, she frequently calls out or lashes out on Billy for whatever dumb things he does, even though she herself does these exact same dumb things Bully does for this reason above.
- In one of her absolute worst appearances, in "Scary Poppins", where she brainwashes everyone in Endsville (except Grim) to follow her orders instead of becoming a better person.
- In the episode "The Greatest Love Story Ever Told Ever", it is revealed that she only agreed to go on a date with Nergal Junior just so she can watch him and Irwin fight over her and ruin Valentine's Day for everyone.
- She is at her absolute worst, where she has hit rock bottom in the crossover special "The Grim Adventures of the KND" where she confronts and holds Numbuh 1 hostage just so she can rule the entire KND organization for world domination.
- Similar to Billy, she barely gets punished for her actions, making her a Karma Houdini.
- She wasn't as bad as she was in the first four seasons, and she redeemed herself in Cartoon Network: Punch Time Explosion.
- Speaking of which, she can still be occasionally tolerable in a few episodes.
- There were still a few moments where she cares about Grim and Billy, especially in the first film Billy & Mandy's Big Boogey Adventure where she showed sympathy towards Billy when she thought that the sea monster ate him.
- Grey DeLisle still did a good job voicing her.
- Series creator Maxwell Atoms confirmed that Mandy, like Billy and Grim is on the Autism Spectrum, which somewhat explains her mean and antisocial behavior.
- Because of her being more evil and mean in these seasons, it is highly likely that Mandy is made to be hated.
- Despite everything, she still cares about Billy and Grim.
- There are some episodes where she is tolerable, and even nice, like "Billy & Mandy vs the Martians", "El Dia de Los Muertos Estupidos" and "Billy and Mandy Moon the Moon".