The red headed heroine with the flashing emerald eyes and temper to match is so common, you might never realize that red hair is natural to only about 1% of the total population. (Higher for those of Irish and Scottish descent, like in the 35 - 45%). Red is a recessive trait, which means it requires two parents with it (the trait, not necessarily manifest red hair) to produce a red headed child.
And interestingly, while blonde hair and blue eyes are genetically linked, eye colour is not linked to red hair. However, the majority of redheads have brown/hazel eyes, not green eyes. Blue, being a recessive trait, means that blue-eyed red heads are the rarest of all.
So what, right. But it's character research. There was talk on a forum recently about how most romance leads are either dark or blonde. Think about that for a minute. I didn't get involved, because I'm already so good at pissing people off. But as it happens, I'd already decided to give a future male lead some glorious auburn or strawberry blonde curls, and I so wanted to avoid the red hair-green eyes cliche. Voila, research. And a post is born. And a character named Erik with dark hazel eyes and copper curls across his brow will soon drag an unsuspecting stranger to his family reunion. Or maybe his sister's engagement party.
Also, I'm dying my hair.
I started writing, or rather being brave enough to share my writing with other people, by dabbling in fan fiction. My chosen fandom was Fantasy Island, which was good for me, because the main characters had no real backstory, and there were two-three guests per week with original stories to tell. That meant very little canon to worry about and lots of creative freedom.
The standard disclaimer was about how Fantasy Island wasn't mine, no infringement intended, and lots of names about who owned it at the time (Sony, among others). Credit where due, and all that. Also the "written for love not money" because using other people's work for no profit is totes okay.
In fan-fiction. Depending on the generous nature of the copyright holders. Who generally don't object. But they could if they wanted to. And some have!
However. The idea that one can use someone else's work so long as you don't make money from it has spread to other areas, images in particular.
I was rather distressed to discover this attitude on a writing site, where "please don't steal my stories!" is a common plea. Because some writers there seem terribly protective of their own work, while stealing others without a qualm.
Images. They make book covers for their stories, which is fine, I do that, too. It's fun. It's a great form of procrastination and it helps you feel like a "real writer", I get that. But the idea that "most images are free to use so long as you don't make money from them" is very strong there.
Sorry, kids, it doesn't work like that. Images aren't born out of thin air, they were created, just like your stories were created by you. The rights to use those images belong to the creator and it doesn't matter that it's "on the Internet" -- you're posting your story "on the Internet" does that mean I can change a few names and call it mine, so long as I don't make any money from it? No?
Google actually has a usage search in the image search function, so you can search for images free to use for non-commercial purposes, either modified or without modification. Photographers and graphic artists get to decide that.
Otherwise, it's just as much stealing as downloading movies and music. But it's a little hypocritical to cry "don't steal my ideas!" over your own work while posting it with a cover made of stolen images.
Back in the days when writing had rules, one of 'em was "Write what you know"
Since I don't know what it's like to be blind in the 19th century or a thief in any century, I've always taken this to be mostly about creating realistic characters before putting them in situations we imagine. Of course research helps. Digression: recently read a blog where the author suggested that skipping research is better for the story. I wept.
That said, do we always remember all the people who've influenced our characters? I thought back to all the guys I considered attractive since I was old enough to have those thoughts.
Then out of the blue, I remembered Gerald. He was two grades behind me and I didn't have a crush on him, I just thought he was pretty. Until seeing him, I hadn't known boys came in pretty. He had big brown eyes and dyed blonde hair that fell across his eyes. With dark roots, and a casual, constant swipe at his hair, he was just adorable. I eventually dug out my yearbook to look him up; my memory is kinder than the yearbook photographer.
I guess he came to mind because I started writing younger male characters, prettier male characters. And I was drawing on my memories of him to "write what I know."