Although Mrs. Luella Bates Washington Jones (I love that name!) at first appears rather rough and gruff, the things she says to Roger and the way she reacts to him as the story progresses paints a bit of a different picture.
Initially, Ms. Jones is incensed and outraged that the boy tried to steal her purse and questions him "Why'd you want to do it?"
Then, as she drags him home to her house, a different side begins to emerge. She takes him home instead of to the police so that she can feed him because he has no one at home to do that for him.
While at her house, Ms. Jones hints at some not-so-pleasant details of her own past in which she alludes to the fact that she herself did some things when she was young that she is not so proud of--the reader can then understand why she is being so nice to this would-be criminal.
So, what kind of person takes a petty thief home and feeds them? A very kind and understanding one.
As for using details in the story, pick out specific sentences of the things that Ms. Jones says and does to prove what you are claiming--for example, if you are saying she is kind and understanding, how do you know this? Where in the story does it show her acting this way?