Archetypes are nice, and we all know and love them. But what about archetypes that combine? Or transform through the story arc to something else? Personally, I think that as a character grows, their archetype will (hopefully) change. I also think each archetype needs it's own complete story arc (beginning, middle and end) before the transformation occurs.
For example, if I have a character start out as an Outsider, and then he becomes a Mentor, I don't just switch to a different archetype.
I let the Outsider aspect have its own complete story arc (with a beginning, middle and end) before the character transforms to a Mentor. This will usually (though not always) happen before the end of the book. If there is a sequel, the Mentor archetype story arc then picks up and continues.
In other words, character archetypes can be a subplot for me.
If I know before I actually do any writing that a character's archetype will transform, I try to do a little blending. Some foreshadowing of the archetype to come. There are some I would probably never blend (for example Hero/Herald) but many of the others can be blended in surprising ways.
For example, I think the shape shifter/mentor have been blended so often that it became the trickster archetype (though I'm sure others have their own opinions about this).
Now, you'd never know it to look at me, but I'm a rule breaker. so as soon as I thought "I would never blend Hero/Herald") I started to think about ways and reasons to blend those two types. I started to see if I could mix and match any two types. So here are my quick thoughts on blending and transforming.
Hero is a natural to be combined with a Mentor. Usually to a kid, that idolizes the Hero, who then takes this opportunity to teach him something. Heinlein did it in "Glory Road", and I think a strong case could be made for Obi Won Kenobi as a combined Hero/Mentor, depending on which of the movies you're watching. "Shane" is probably that way, too.
Hero and Threshold Guardian. Hmm... I don't see it. Something to think about. Maybe an aspect of the Hero's personality could be the Threshold Guardian, but I can't see it working well. (Aha! A challenge!)
Hero and Herald. This one I think is impossible. How can the Hero act as his own Herald? (Oh, wait. Prophetic trances?)
Hero and Shape shifter, been done to death, I think, as the anti hero.
Hero and Shadow. It could be (and frequently is) the "dark side" of the Hero's personality. So, yes, this one gets combined a lot.
Hero and Trickster. I'm thinking Gambit from "X-Men" or Ananzi from "Static Shock". Could be done well, and isn't over done. Some good possibilities I think, but not as a view point character. (Hmm.. I wonder if "Star Girl" would qualify? I haven't read it. Which leads to glamor bombing in general, which leads me to realizing that these archetypes could combine well and be used as a view point character. Not overdone, either.)
Mentor and Threshold Guardian. Probably done to death and I'm not going to do it unless I think I can do it better.
Mentor and Herald. I can't think of any examples off the top of my head, but it's an easy mix.
Mentor and Shapeshifter. I think I'm going to do this with Oubliette. It's not overdone, but I'm sure I've seen a couple of examples of it.
Mentor and Shadow. I can't think of any examples, but again, I think this one is a natural.
Mentor and Trickster. Raffiki in "Lion King", and if Disney is using it, it's over done.
Threshold Guardian and Herald. That's an easy mix.
Threshold Guardian and Shape shifter. That's another easy mix, but at least a little more intriguing.
Threshold Guardian and Shadow. Eh, nothing to write home about, but looks like an easy mix.
Threshold Guardian and Trickster. Oh yeah, been done a lot, but still things of interest to tap into here.
Herald and Shape shifter. Easy!
Herald and Shadow, more complicated than it sounds, I think.
Herald and Trickster. Easily done, but I can't think of too many examples. There may be untapped riches here.
Shape shifter and Shadow, way too easy.
Shape shifter and Trickster. Way too easy.
Shadow and Trickster easily done.