4 – Do you have a "muse" character, that speaks to you more than others, or that tries to push their way in, even when the fic isn't about them? Who are they, and why did that character became your muse?
Well, shortest answer ever.
I guess in the latest story I've been writing, which is the Potions part of Purgatory, Prophets, and Potions - it's been Teddy. Though, the story is legit about him... but there's stuff that I really wanted to put in the story that I didn't get a chance to - like, why Teddy is hung up on Vicki even though she's basically his cousin and it's weird, and stuff like that. I find Teddy pretty fascinating as a character, mainly because I've given him a complex sexual identity and, really, a complex interior life over all.
Other than that, I like my OCs - Till often ends up in the demented'verse, largely because I need a medic. Nate is also a favourite of course - to the point where i wrote a Marvel/Nate crossover for fun once.
The problem with Nate is that because the story isn't about him, but he often shows up wherever Teddy is, I sometimes fear that he comes across as a bit too perfect. I just can't explore Nate's shortcomings and interior life the way I can with the canon characters, and it's because the story is never about him.
Anyway, other fandoms, other stories? Nope... can't say that anyone ever forces their way.
ETA: Might as well answer question 5, since it's related:
5 –If you have ever had a character try to push their way into a fic, whether your "muse" or not, what did you do about it?
Like I said - it never really happens. But, if it does, then I just look at the situation - does it make sense to have that character there? Am I giving them all the good stuff to the detriment of the other characters because I like them better? If the character doesn't make sense, or I'm overusing them, then I cut them out or cut back on what they do. It's as simple as that - it's the old (actual) "kill your darlings" rule. If you're holding onto something that is damaging the story, just because you like it and don't want to cut it, then you've got to LET IT GO. Having that one witty line, or that one awesome moment, or that one character, isn't worth it if it makes everything else suck.