Not so Above It All: Meg is the most responsible and level-headed sister but she can be vain and self-indulgent on occasion — if not boderline greedy. Also, after her marriage she makes some questionable decisions, as a wife and as a mother. Of course she learned her lesson at the end.
Important Haircut: One of Jo's turning points in the first book was willingly cutting and selling her gorgeous Rapunzel Hair to help the family after Robert falls seriously ill and Marmee must go take care of him. Everyone reacts as if she was the victim of a Traumatic Haircut, but Jo is calm about it... until she's alone with Meg that night and confesses that it wasn't as easy as it seemed.
Ill Girl: She had scarlet fever in the first book. It doesn't seem much now, but actually scarlet fever can have very serious side-effects in the heartthat were fatal and untreatable back then, and those are are what killed poor Beth in the end.
Break the Haughty: Twice, in the first book. First, she's punished and humiliated at school when she attempts to be In with the In Crowd and breaks school rules to do so. Second, when she replaces Jo temporarily during Beth's illness... and has a HARD time pleasing Aunt March.
Jerk with a Heart of Gold: She has a good heart behind her vain and self-centered behaviour. In fact, she breaks down crying in the first book when she writes her own testament while Beth is sick, and then the very possible prospect loss of Beth sinks in.
Jerk with a Heart of Gold: If she does like you, she might help a little. She genuinely liked Amy despite giving her a hard time, and when she died, she left her Plumfield house to Jo.
She complains about and criticizes her nephew's family to the point where Marmee can barely stand her, but due to the family's poverty, she offered to adopt one of the girls, supplies the money for Marmee to visit Father, surreptitiously provides Meg with an enormously overstocked linen closet as a wedding present despite swearing not to, and Amy notices that, for all of her riches and treasures, the most precious to her is her wedding ring. Aunt March is a cross, sour old lady, but she definitely has the heart of gold down, too.
Unfortunate Name: His last name, which is not "bear" or "beer." Often lampshaded in the book, particularly when Laurie refers to Plumfield as a "Bhaer-garten," punning off the German "Bier-garten."
John Laurence "Demi" Brooke
Incorruptible Pure Pureness: He's very well respected and admired among his classmates for this reason, is above reproach in any serious trouble (though he's still a little naughty sometimes), and the other boys wouldn't even consider attempting to convince him to do anything really morally wrong.
Punny Name: He's named after his father, so the family would have been stuck calling him "Jack" to keep from having two Johns running around, but Laurie suggested naming him "Demijohn" ("Little John") and calling him "Demi" for short... which also happened to be alliterative with the nickname Aunt Amy gave to his twin sister.