Ellen Wilson came to Malory Towers when Darrell Rivers was in her second form, and was known to be a serious, scholarship girl. Later in the book it was shown that she was snappy and irritated if you accidentally jerked the table when she said she was reading. Ellen got tired in class, and coughed a lot. When she was accused of stealing the second form's purses and trinkets, she decided if they thought she was a thief, she may as well cheat on the exam paper coming up, since her brain didn't seem to work anymore. Darrell Rivers found her, and they had a fight once again where Darrell lost her temper and called Ellen a thief and a cheat. Later that morning Ellen was discovered not in bed, so the whole Second Form all assumed she had been expelled for stealing. It turned out she had gone to Matron with a blinding headache, because she had overtaxed her brain. Miss Grayling came to see her and she thought she was going to be expelled. Her people were probably very poor, and payed a lot to buy her uniform and things, which gave Ellen a lot of stress. She recovered soon after, and was moved to the Fourth Form in the third book.
Ellen's personality did not show much, as she should be not usually snappy, and seemed nice enough when shown a peek in the third book. She is quite clever and not selfish. Ellen also is eager to please her people but overworked.