Introduction
In my own "How To Write A Warriors Fanfiction" book found on my personal account (LightningStrikeTC ), I really went into detail with the topic about characters. I mentioned the what to do's and what not to do's, and my advice will be taken straight from my book, but it will be slightly different! If you've read my guidebook already, then I think you're good to go.

The Importance of Characters
The importance of characters is really great, because they make up what your book is about. Characters often have things about their personalities that makes your book special and unique. They are what narrate the adventure, what build up the plot, and fill up the gaps of your Warriors Fanfiction. The significance of the character and how great you consider to build them up is one of the most important things you must never forget, so let's get started.

What not to do.
Don't make your character a Mary Sue! I hate those to death because Mary Sue means the perfect character, and the perfect character is boring!

Perfect characters always have perfect hunting skills, social skills, fighting skills and leadership skills. Their looks are beyond amazing---never a fur out of place. They never make mistakes. They are always right and always amazing; faster than WindClan, cunning as RiverClan, stealthier than ShadowClan, more heroic than ThunderClan. These are all great qualities that the Clan cats work for, and characters can't have all these skills because then, the adventure will be boring.

(Guys, don't always make your characters belong to ThunderClan as well. That is annoying because, well, maybe ThunderClan is becoming overused. I love TC and am a TC person myself, but I always considered myself to be a RiverClan cat at heart :3)

So, do not make your character have perfect looks.

Do not make your character have perfect qualities . . .

. . . or your fanfiction will be in great lack of character development.

What to do.
In a Warriors Fanfictions, there are lots of things you can do about your character development to make your story line more interesting as you go on.

For example, maybe they can have something about the way they talk that excludes them from every other cat. Maybe they have a certain personality that is weird (like Tallstar). Maybe they are quirky, funny, mean, or emotional (like Bluestar). They can even have something about the way they look that makes them different (like Crookedstar). Heck, they can even be trouble makers growing up (like Firestar).

Those were all examples that you can give your character to make their development good. There are many more things as well that may make them special and unique, but these are just a sample of them taken from the books themselves. Now enough of examples, there's more at what you should also do.

What's great about a book is how your character gradually builds up a personality if you do a story about a character from kithood. Keyword: build up. Thats right, build up your character. As they grow, they could be clumsy hunters or even clumsy fighters, but they might be strong and great in another quality. If one of their loved ones or Clan mates die, it can also effect how their personality may change.

There are many other ways to build up Character Development, but these are some of the basics into it. Being a great writer doesn't mean just following the plot, but making it better with a great character that gradually begins to grow into something that ties the whole point of your book all together. Never forget the significance of Character Development, and I assure you that you will be satisfied with the results!

~~LightningStrikeTC