Well, here's what everyone's been waiting for: Part 2 of my essay! :) before I go any further, I'd just like to thank everyone for all the positive feedback. Always nice to hear. Anyway, where was I? Oh! The essay!!!
Motivation, or: Why characters do anything at all
This is a section of my essay I want to put special emphasis on; as this is pivotal when writing fanfictions or just writing in general. Now, in Brian Jacques' original Redwall series; villains tended to have simple goals to drive their ill-matched visions of power and ambition, and villain backgrounds and personal information tended to be fairly rare. When writing your fanfiction this does not have to be the case.
When writing your fanfiction, it would help if you made your characters' goals especially personal; even the villains. It helps the readers understand them more as characters, to know WHY they do the things that they do and how they got to think that way.
Sadly, one-dimensional villains are all too common in children's books and films; and with a few exceptions the Redwall series was more inclined to this norm. The world of Redwall was VERY black and white with very rare 'gray' exceptions, and most of these gray characters that were atoned vermin died VERY shortly after reforming (See: Romsca, Veil).
When writing your main antagonist, no matter how sadistic they may be, it is critical that you mention that the villain in question doesn't regard themselves as evil. As I read on an an internet writing tutorial; every villain should be a hero in their own eyes and I agree completely.
An issue that constantly plagues aspiring writers is characters that are TOO perfect. Such characters are referred to as Mary Sues, and no they can't exist in real life since there's no such thing as an idealized person that EVERYBODY adores and worships.
Make your characters emotionally real, with their own individual flaws and weaknesses, families and home lives, ecetrera. If they go through something emotionally painful emphasize that they actually ARE suffering and not just attempting to get pity from other cast members.
And finally, PLEASE make sure none of your characters are too powerful. If you want to have a physically strong character that's perfectly acceptable; but just don't have them running around lifting up buildings with their bare paws or killing creatures just by poking them in the skull. Redwall may be a fantasy universe but it DOES have realistic laws of physics, so please try to pay attention to this.
Also: If you want to have a weak, fragile (typically female) character that's fine; but it's not particularly advisable to populate your story with many of these characters who CONSTANTLY need to be rescued, thus distracting the heroes and bogging down the plot.
I hope the following editorial has proved helpful in your writing enterprises. If you ever seek to write a Redwall fanfiction but are in need of ideas, character suggestions, etc, feel free to post a message on my wall here and I'll do my best to help you out :)