Ashley is a fellow student Sal meets in Chapter 2 while heading inside Todd's house to ask him about the ghosts in search of help. In Chapter 3, we see much more of her. She is one of Sal's classmates, and she seems to have grown very close to the main group.
Larry and Todd were completely okay with the thought of killing Miss Packerton, but she and Sal were reluctant with helping them plot the murder, but thanks to a convenient car accident, they didn't even start making the plan.
In chapter 3, Ashley is shown to have a bit more personality, along with a better role of helping Sal with his bleeding face when punched by Travis, showing she is quite kind-hearted and accepting of Sal even when the mask is off of his face, and helping with the bologna mystery. It should be noted that she is the only one in the group that does not believe in ghosts.
She loves art and she is the best artist in the group. Ashley is revealed to have been an old friend of Larry's and she is the one who taught him everything he knows about art.
At the end of Chapter 3, it is revealed that she will testify against the Sally Face Killer.