Here's why:
* Stereotypes are often flat: They tend to be one-dimensional, representing only a single trait or a small set of traits. The classic "evil stepmother" stereotype is flat, often presented as cruel, jealous, and manipulative.
* Specific characters can be round: However, a character who is a stepmother in a story might be far more complex than the stereotype. A writer could develop this character with depth, giving them motivations, internal struggles, and a full range of emotions.
To determine whether a specific stepmother is flat or round, you need to consider the following:
* The story's context: How is the stepmother presented? Does the story reinforce stereotypes, or does it challenge them?
* The character's development: Does the stepmother change over the course of the story? Does she have complex motivations and relationships?
* The author's intentions: Does the author intend to create a simple, stereotypical character, or a more complex and nuanced one?
In short, the answer to your question depends entirely on the specific stepmother you're referring to and the context in which she exists.