Oh, a lot of things, trust me.
Sometimes - heck, at least half the time - it comes from something in the movie; heck, it's often just one little thing. "The Major and the Nutcracker", for instance, was basically inspired by one line Captain Candy said; "we've tried everything else to defeat the Mouse". This got me thinking about what they got up to before Clara and Eric showed up and it eventually led to that story. I've also been inspired by a character's behaviour or even the way they spoke. I've also written fanfiction simply because I'm curious about something and I wanted some kind of answer.
I've also been inspired by music. Dreams... not so much, because I barely remember most of them and no one I write about ever shows up in them anyway. Sometimes I even get inspired by other fanfics.
Sometimes - heck, at least half the time - it comes from something in the movie; heck, it's often just one little thing. "The Major and the Nutcracker", for instance, was basically inspired by one line Captain Candy said; "we've tried everything else to defeat the Mouse". This got me thinking about what they got up to before Clara and Eric showed up and it eventually led to that story. I've also been inspired by a character's behaviour or even the way they spoke. I've also written fanfiction simply because I'm curious about something and I wanted some kind of answer.
I've also been inspired by music. Dreams... not so much, because I barely remember most of them and no one I write about ever shows up in them anyway. Sometimes I even get inspired by other fanfics.