Morveren is considerably more hotheaded than her twin sister Jenna is, and doesn't appear to do well in class. She had detention on the last day of school. However, despite these faults, she is more accepting than Jenna is, as she wanted to help Malin more than her sister did. Morveren can be caring and is very protective of her family, as shown when she did her best to retrieve her brother Digory from Ingo, and when she gave up a chance to stay in Ingo to stay with her sister. Morveren can be a little overcautious, and is stubborn. She dislikes and distrusts Bran Helyer despite his relationship with Jenna.
Her family includes her older twin sister Jenna, her parents, and her younger seven-year-old brother Digory. Her family is the Trevails.
- Morveren Trevail is not to be confused with the mermaid Morveren, who is the Mer woman who lured Mathew Trewhella the First to Ingo.
- Morveren's name means "Mer girl", as the first part of her name (Mor) is a name of the Mer. Thus we can assume that "veren" means girl.
- Morveren and Malin's relationship seems to be similar to Sapphire and Faro's relationship, with the main difference being that Faro and Sapphire are much closer to each other than Malin and Morveren are.