Granny Deaver is a slovenly old lady who has been living with Kelly's family for the past three years. Despite being called Granny, she isn't actually related to the family, but was a friend of their late aunt. Despite her gross and obnoxious behavior, Kelly's parents decide not to get rid of her due to her having nowhere else to go. Eventually, she passes away. Kelly's family are the only ones to attend her funeral since she had no friends or other family members. But when the family go home to celebrate, Granny Deaver's ghost soon returns, now with even less incentive to leave the family alone. She continues to be a burden and even ruins Kelly's birthday party. Overtime, her body begins to decompose, while also gaining a more nightmarish figure whenever she gets angry.
Kelly's family, having no other option, consider moving out, only to return home to see that Granny Deaver has caused noise complaints among other things. The monstrous Granny Deaver then tries to attack Kelly, but because she's a ghost, can't actually harm Kelly. Granny Deaver, now defeated, just leaves. The family breathe a sigh of relief, but it's short lived as more ghosts arrive at their house, having been invited to stay by Granny Deaver.
The story doesn't go into much detail on her physical appearance other than the fact that she is a very gross person. Her ghostly form begins to decompose rapidly overtime, making her even more gross and creepy. In her more monstrous ghost form, she grows fangs and claws.
Granny Deaver is a gross, slovenly, mean old woman with no sense of boundaries or personal space. She'd loudly slurp soup, or even wipe her mouth with Kelly's art project. When she dies, her ghost is somehow even more gross and obnoxious, often howling all night. She is also very quick to anger, especially when it comes to people who don't like her, particularly Kelly. This turns her into an even more frightening ghost complete with fangs and claws.