Some examples:
Obi-Wan Kenobi is considered the classic example of a Mentor. He shows Luke what he could be and how to get there.
But he does not stay in the Mentor all the time. The emotionally powerful scene where he confronts Darth Vader is created when he steps into the Hero role. He is moving the action in that scene, not merely instructing or demonstrating things to Luke. When a character shifts archetypes for a scene, the stakes go up. No matter how many times I see Star Wars, I cry when Obi-Wan is defeated in the light saber scene. This intense emotional reaction comes from him changing his role in the movie.
A second reason to think of the archetype as a role and not a personal characteristic is this creates a fuller, more interesting character in your story. If your Mentor just sits around dispensing wisdom and pithy comments all the time, well....Ok, let's face it. That is boring.
If your character delves into a new archetype, they are suddenly deeper, truer, more emotionally resonant people. Don't think of archetypes as limiters.
They exist to liberate your creation.
