Jacobs’s text is pretty straightforward, and her language is generally simple. This simple style extends to her characters, as she basically just comes out and tells us what to make of them. When characterizing Dr. Flint, the narrator refers to him as “crafty” and a “vile monster” (5.1). Alrighty, then. Dr. Flint, crafty monster.
In contrast, Aunt Martha is a “woman of a high spirit” on whose “faithful bosom” Linda can always depend (5.3). Check and check. When it comes to these characters, WYSIWYG.
What you hear is also what you get in Incidents, as character dialogue is especially revealing.
Dr. Flint reveals his tyrannical ways as he shouts, “Silence!” to Linda when she tries to rebuke him (7). He verbally threatens to kill Linda; he whispers dirty things in her ear that we (thankfully!) don't get to hear. Aunt Martha also reveals herself as a spiritual guardian and source of comfort when she consoles Linda with words like, “Poor child! Poor child!” (8).
The biggest giveaway, though, is when Jacobs uses speech to clue us into her characters' social status and education. When poor whites raid Aunt Martha’s house looking for signs of a slave rebellion, for example, they speak in Southern dialect: “We’s got ‘em! Dis ‘ere yaller gal’s got letters!” (12.7).
Linda, on the other hand, was taught to read and write by a refined white mistress. There's no trace of slang or dialect in her speech: “You were not sent here to search for sweetmeats” (12.9). This is all the information we need to figure out that she's way superior to her tormentors.
Of course, Linda also uses the same kind of dialect to show that she's different from other slaves. When she runs into fugitive Luke in the North, she gives us a little taste of his speech:
I tuk car fur dat. I'd bin workin all my days fur dem cussed whites, an got no pay but kicks and cuffs. So I tought dis nigger had a right to money nuff to bring him to de Free States. Massa Henry he lib till ebery body vish him dead; an ven he did die, I knowed de debbil would hab him, an vouldn't vant him to bring his money 'long too. So I tuk some of his bills, and put 'em in de pocket of his ole trousers. An ven he was buried, dis nigger ask fur dem ole trousers, an dey gub 'em to me. (40)
Got that? Because we sure don't. But we don't think that Linda is trying to make fun of him or show that she's superior to him, because she goes on to feel sad about how Southerners keep slaves in such ignorance. Instead, she seems to be suggesting that she has to speak for these people who can barely speak for themselves.