Complete Monster: In the 2013 BBCFilm of the Book, Adeline March is the unstable and violent twin sister of Emmeline and cousin of Vida Winter, who described Adeline as "genuinely dangerous" and that "violence was always her first instinct". The twins, inseparable while growing up, had the run of the house while children and caused all sorts of havoc, which came to a head when the two pushed a baby in a carriage down a hill. When the local doctor's wife came to inquire about the incident, Adeline, who was nine years old, hit the doctor's wife in the back of the head with a violin. The twins' mother was blamed for the incident and a governess was hired to instill discipline. On the first day of school, Adeline stabbed Emmeline in the ankle with a pencil. The twins were separated for a time to see if they would improve but to no avail; when the girls were reunited, Adeline gave Emmeline a No-Holds-Barred Beatdown. When the three girls were 17, Adeline murdered two of the servants, Missus and John-the-dig; the former For the Evulz, the latter because he acted as a mentor to Vida. After Emmeline gave birth to a son, Adeline attempted to murder him, eventually setting the house on fire and severely burning Emmeline before being left to die by Vida. Adeline was willing to cross any line to receive attention and didn't care who she hurt in the process, with her actions casting shadows to the present.
Fridge Logic: Vida Winter wrote dozens of novels with her non-dominant left hand, in fact used only her left hand for years and years — yet her handwriting never improved beyond a childish scribble?
I thought the letter Margaret received was written with her dominant right hand, ignoring the pain to become the first - and only - thing she wrote with that hand after the fire.
There's plenty of people who write like crap with their dominant hand after years of knowing how. Unless someone actively strives for pretty handwriting, the vast majority settle for "hey, people can read it--why bother?"