Gretta is extremely rude and obnoxious towards Beverly, because of rumors about her being promiscuous, and bullies her at every chance she gets.
She isn't too nice to Bill and his friends, either, and teases them a lot as well. An example of this is when she writes "LOSER" on Eddie Kaspbrak's arm cast.
Gretta is first seen storming into the girls' bathroom and harassing Beverly, calling her a "slut", a "little shit", and "trash", and one of her friends calls Beverly a "loser" while dumping a garbage bag on her head. Fortunately, Beverly holds her backpack above her head, protecting herself from the disgusting garbage within the bag.
As Bill, Eddie, and Stan are in Mr. Keene's pharmacy getting supplies to help Ben recover from the injuries Henry Bowers caused him, Beverly comes into their aisle to avoid Gretta, who is just leaving the pharmacy, and distracts Mr. Keene so they can sneak out with their supplies.
Later on, when Eddie comes to the pharmacy because of his broken arm that Pennywise caused, he speaks with Gretta, and she writes "LOSER" on his cast, though he writes a "V" over the "S", making it say "LOVER" rather than "LOSER".
It: Chapter Two
Gretta is briefly seen as an adult when an older Eddie comes into the pharmacy, looking for his childhood artifact, his inhaler.
And like most of the other characters, she is seen as her younger self.
Differences from the source material
- She is the one of the characters who are never introduced in the original miniseries.