Authors, in writing characters that float around in their heads, also fear the Mary Sue.
According to urbandictionary.com: Mary Sue
But how do you know it's a Mary Sue? Some of them are obvious (coughmyfanfictioncough). I found this last night: the Mary Sue Litmus test!
Mary Sue Litmus Test
I read fanfiction--less so these days--but I get caught up in the stories, even though they're not exactly well-written or well-plotted or anything. And obviously, any "real people" fic where the hot actor/musician/really sexy dude falls in love with the overly intelligent/beautiful but doesn't know it/ordinary woman and then they go forth and have lots of sex....It's the closest I'm going to get to any of those guys.
So I ran a few of my characters through. Madeline earned a 24: a Borderline-Sue. (But let's fact it, it's a romance novel. It's helpful if she's attractive, intelligent and likable.)
Let's do her love interest, Henry. (half-Indian jaded spy, who has to lie to Mady to complete his last task as a spy. After that, he can go run the shipbuilding business that his father left him). He's a 24, too. Aww. They're a match!