She and her friend Sour Susan also got Horrid Henry and Rude Ralph in trouble at school in "Horrid Henry and the School Uniform". At the very end of the episode, they tease Henry and Ralph, who retaliate by throwing slime that hits Miss Battle-Axe and Mrs. Oddbod by accident. Henry and Ralph get chased by them; while Margaret and Susan get away with it scot-free, this makes the two girls karma houdinis.
Her worst role where she is at her absolute worst of them all comes in the season 3 episode "Horrid Henry's Unhappy Day", where she steals Henry's comic; makes Henry do humiliating things, and breaks her promise about giving him the comic, meaning she spent the whole episode abusing him without any punishment.
Relating to BBBBQ#2, she barely shows any kindness to Henry as she lives just next door to him - even Perfect Peter, Henry's younger brother, has his kind moments to him.
She's extremely bossy. She believes being a host and guest both mean that she is declared as being in charge.
Whenever she goes to her friends' house, she's the guest and everyone must listen to her, though when guests come to her house, she bosses them around because it's her house, making her domineering in an obnoxious way.
Like Perfect Peter, her voice by Sue Elliot-Nichols can be very annoying at times - especially when she raises her voice or screams.
Her character design is decently cute and easy on the eyes, especially compared to Miss Battle-Axe.
Despite her hatred of Henry, she actually helped him and is nice to him in some episodes, as seen in "Horrid Henry's Horrid Revenge", where she participated in Henry's plan to get back at Peter by getting him into trouble with Henry's Dad in exchange for letting her be the leader of the Purple Hand Gang for the day and the following day.
Her dislike for Henry is somewhat reasonable since he also hates the opposite sex and bullies her often.