How does Tris change as the story progresses? Is she a reliable narrator?

In the story, Tris sheds her shy, awkward image for a warrior persona in the space of a short period. Although the transformation is impressive, Tris’s account of her experiences demonstrates just how difficult her adjustment has been. Upon leaving Abnegation, our heroine is thrust into a terrifying world populated by bullying peers, formidable authority figures, and a shadow government that seeks her demise. In this new world, she must also process the unfamiliar new feelings that Tobias awakens in her and endure numerous trials that test her psychological resilience. To her surprise, our heroine learns that the fear simulations reinforce her divergence, a trait that propels her to decisive action on behalf of her beleaguered city.
As for whether Tris is a reliable narrator, it is evident that her objectivity is sometimes questionable. For example, Tris resents Tobias for "throwing knives" at her and scolding her at "every opportunity" during training. However, it is evident that Tris’s perspective has been skewed by her naïveté and ignorance. It is only after Tris learns about the murder of Tori's brother that she begins to understand the rationale behind Tobias’s austerity.