This is the kind of characterization that is used most frequently in this book. Each character, no matter how minor, gets some sort of an introduction, often paragraphs long. Mr. Yates, for instance, isn't the biggest player in the book, but he gets a couple of pages of narrator commentary after we meet him. The narrator also frequently jumps back in throughout the story in order to tell us things directly about a character's thoughts, feelings, actions, and such.
While the narrator often tells us these too, the characters also speak for themselves. Well, certain characters do, at any rate. For some characters, like Julia, we get practically no direct dialogue; the narrator tells us Julia's thoughts and opinions herself. However, other characters like Mary and Henry frequently express their opinions and debate issues themselves. Opinions are crucial in determining who does what and who hooks up with whom in this book. Edmund and Fanny in particular judge people on their opinions. In fact, the opinions that Mary expresses over Henry and Maria's affair are what cause Edmund to end their relationship.
The lack of dialogue is often a more significant method of characterization than actual dialogue in this book. Fanny is largely defined by her silences – through them we understand her shyness better. Julia's silences, meanwhile, help to reinforce her role as a background figure in her own family, always playing second-fiddle to Maria. And Edmund and Sir Thomas are frequently described as "silent" and "grave," which means serious. Silences can thus accomplish a lot of different things and can tell us different things about our characters. Silences often "speak" in different ways too, conveying a character's fear, shyness, anger, disapproval, etc. to the audience.
These silent characters contrast with the novel's chatterboxes. Characters like Mrs. Norris, Henry, and Mary dominate with their dialogue. The narrator often lets them speak for themselves instead of jumping in to characterize them for us. In chapter thirty, for example, Henry and Mary have a conversation that lasts the entire chapter without interruption. The narrator only jumps in a few times here.
This is a major method of characterization in this book, which makes sense given how class-conscious, money-obsessed so many of the characters are. Money and social rank guide our characters' actions and choices. For instance, a running theme in the book is why people get married – do they do it for money and social advancement or for love?
Though it's up for debate, social status also seems to shape the characters' personalities. London and money made the Crawfords who they are as much as poverty made Susan Price who she is. Fanny in particular is impacted by her social status at Mansfield. She's often treated like a second-class citizen, especially by Aunt Norris, and is often reminded that she isn't really "equal" in terms of social rank to her wealthy cousins.
Though the scenes involving horseback riding aren't very numerous, they are very important metaphors for one of the book's other major themes: the tension between activity and passivity. Characters are clearly defined by how they ride horses, particularly Fanny and Mary. While Mary is a very good rider who likes to ride very fast, Fanny is a timid rider who can only go at a walking pace and with a person along to help her. The riding scene that occurs with Edmund and Mary in Chapter 7 is a crucial introduction to Mary's character and helps us to really visualize the contrasts between the bold and strong Mary and the weak and shy Fanny.