It's a whole bunch of TV characters. Canonically, I need to accurately represent at least 8 separate characters before getting into original content. I'm not attempting a crossover so I've got that going for me.
Yeah, I don't recommend a crossover as your first fanfic attempt. It's hard enough to pin down one set of characters. But keep practicing, and have someone beta read it - preferably someone who is very familiar with the source material and who isn't afraid to tell you where you don't have it quite right.
One thing to avoid is the use of modern, RL slang and other words and phrases that are anachronistic or inappropriate to the source material. I recently read a
Bonanza story in which the author had one of the Cartwrights mention that someone was upset and "needed to vent." That's a modern slang phrase and completely inappropriate to the 1850s/60s and that set of characters.
I like working with the Sliders (original foursome; can't stand the show after John Rhys-Davies quit) because almost anything goes. Another crossover story is Sliders/Xena: Warrior Princess. The way I made that work is using the idea that in this alternate Earth, Alexander the Great didn't die young - he actually made it all the way across Asia and into North America. That's how the Sliders were able to slide into an alternate California and promptly be confronted by Greek temples everywhere. As for Xena et. al turning up in the 20th century, that show was all over the map as far as time went. Why not an alternate 20th century?
My biggest issue in my writing is that I always feel as though my characters are identical in tone and personality. Nuance in interaction is a silent thing that happens and isn't overtly obvious to me, be it in real life or in writing. It often results in me not knowing if I've given each character a unique voice. Since Star Wars Rebels is a Disney show and follows the same pacing as The Clone Wars, none of the characters have particularly groundbreaking quirks in how they act so that adds some difficulty to it. They don't have unique attributes to their speech, barring a couple mannerisms that I do have down pat (Zeb saying "karabast" and Hera occasionally reverting to her native twi'lek accent).
Unfortunately, I can't help with this. I never managed to stay awake for any of the prequel movies, and haven't seen any of the spinoffs. When it comes to Star Wars, I'm a purist in the sense of only the original trilogy (before Lucas decided to "improve" it) counts - as it was shown in the theatre. Well, that and I enjoy a few of the novels.
Sometimes it helps to study the body language. One of my favorite TV series is
The Crow: Stairway to Heaven. The lead actors on that show were amazingly good at conveying very subtle emotions and messages with facial expressions or a slight bit of body language. This is a show for which I started writing fanfic by about the third episode (most of what I wrote was rendered obsolete by later episodes' canon details, so I consider it AU), and some of the stories and poems were inspired by no more than a line of dialogue and a raise of the eyebrows. It made me wonder what the story was behind these actions and reactions, so I decided to write it.
As you write, try to imagine the story unfolding on a screen or stage. If it feels right, you're very likely on the right track. I've read some Bonanza fanfics that could have been real episodes. The characterization is perfect - the dramatic moments, the humorous moments, the character interactions, and the plot is something that could have been made in the late 1950s/early 1960s.
I guess I am just being a worry-wart about it. I've never written a pre-established character or within a pre-established universe. I have always considered it to be beyond me, or at the very least unsure of how to approach it. I'm walking into this blind.
The first rule: Have fun. Fanfic is your take on the characters and what situations you put them in. Since it can't be professionally published, you don't need to worry about pro reviews or whether it will sell.
The second rule: Pretty much everyone will write at least one fanfic that is absolutely awful, horrible garbage. My first Star Trek fanfic was like that, and taught me that writing romance/drama is not my strong suit. That story was so awful, that I don't even care that there was only ever one copy in existence, written in longhand on looseleaf, and it was given to a high school friend as a birthday present. For some weird reason she kept it carefully preserved in a binder - but I sincerely hope that at some point in the intervening 37 years it's been lost beyond retrieval. Damn, that's an embarrassing mess to have my name on.
I have actually found that most of my attempts to write serious material tend to take a turn to the satirical. A friend and I wrote several chapters of a
Star Trek: The Next Generation soap opera parody, in which all kinds of bizarre things happened. That was rather fun to do, and I've been thinking about revising and adding to it.
But my two Camp NaNoWriMo efforts earlier this year were decent starts on fanfic based on F.M. Busby's Hulzein Saga series. It's part dystopian, part space opera, and the intention is to fill in the blanks in the characters' lives. Busby glossed over so much in his books, and one of the omissions had me wondering: One of the main characters fathered a son decades (objective time) before he and his wife had a daughter... and a couple of pages after learning of this, the kid was never mentioned again. So it occurred to me that at some point it was possible they would meet - and since Busby used STL for his spaceships in most of the novels, it's possible that this character and his son could meet and discover that biologically, they're the same age.
A little bit of stream of consciousness writing (good for getting ideas down and maybe jotting down a few lines of dialogue here and there), the basic story started to take shape. I mentioned earlier about doing a novelization of a gamebook; I might change my mind on that and continue with the Hulzein series fanfic. There are many stories left to tell in this, and since the author died some years back, nothing I write can be contradicted (thank goodness, because Busby contradicted himself in some really maddening ways).