The nature of the last reply directly points out why a 'request for characters' do not work for fanfic.
"Look at my roleplays."
That line speaks the truth... now this sounds far more like a roleplay than a fanfic. How can you fully navigate and develop the characters in your story if they are not yours to begin with?
Especially with a "personality" fixed in stone, you're forced to adjust the story to the characters, instead of using characters to express what you're trying to say. We're on the wrong end of the motive. A role play is to use existing characters, and together through them, create a plot out of it. Fanfiction and story are the other way around. You weave a story, and bend the characters if necessary in order to get the point across.
In conclusion...
-role play uses characters and see what kind of a point will come out of it
-fanfic wants to express a point and will bend everything in the world if that's what it needs to get the point across
Wrong motive... wrong motive...
5 or 6 characters are probably far more than enough already. Usually, there's at most a few (perhaps just 3) main characters, along with a few minor cast support. For these types of characters, I recommand you to "make them as you need them." You don't know how the story will turn out as of now most likely, and depending on what you want them to do, they will have to look different or be named differently depending on the context and the situation. Minor cast supports don't require too much planning in the beginning, I think, since the story usually crafts half of their characteristics by default. You just need to fine-tune it later at the very end in the proofreading step when you pick up your own connections within your writing.
As for the rest who are highly disposable to only appear in a few lines, a random name without even character description can do (because they are that unimportant.) Heck with it, just a random title will do, and just screw the name altogether.
Personally, I'm against Light Azumarill's ideas for reading other fanfics for inspiration... more than likely, you'll get more than just inspiration, and in the end, just totally suck the character from this other fanfic, and do a "copy+paste" of it into your story, essentially changing your story to be more alike to the fanfic that you've just read (therefore, losing originality.) If you're suffering from writer's block, the best solution is actually just to stare at it, and write out the "crap" that you think is horrible... A writer came to speak of his writing experience in my university class once, and he said that usually some sense comes out of the nonsense you write up when you think that you can't write anything.
