I suppose the easiest way to describe the difference between a normal crossover and a fusion is using the colors blue and yellow. A crossover is a pattern: something simple like blue polka dots on a yellow background or something complicated like paisley. A fusion is the color green.
Story: The Grandparent Trap
Rating: All Ages
Word Count: 5108
Author's summary: Early into her stay on Dalek war-torn Earth, Susan meets a girl who looks exactly like her. (Doctor/Master)
Characters/Pairings: First Doctor/The Master, Susan Foreman, Sharon, Barbara Wright, Ian Chesterton, Vicki
Warnings: Spoilers for The Dalek Invasion of Earth as well as The Parent Trap, sort of. Needless to say, the plot goes a bit AU.
Recced because: This is the story of how Susan meets her long-lost identical twin Sharon and how they fix up the Doctor and the Master's mess with togetherness. It is my absolute favorite Doctor/Master fic in the world. Which, I suppose, isn't surprising, because it steals its plot shamelessly from one of my favorite movies as a child: The Parent Trap. By which I mean the original sixties version that used to play on the Disney Channel, with Hayley Mills (and Hayley Mills!), not the Lindsey Lohan remake which didn't even exist until I was in high school. (Speaking of Lohan remakes, the original Freaky Friday with Jodie Foster is also way better, although the book is best of all.)
ANYWAY, I am utterly impressed as a fic, both on its own merits (the writing quality is top-notch) and by its merits as a fusion. Every time I reread it I notice new echoes of the original Parent Trap movie. I just love this fic so very, very much and I hope you all will love it too.
“I’m a Time Lady,” the other girl said, which was also a very silly thing to say on Dalek-infested Earth, where the lords and ladies of time were not exactly welcome dinner guests.
“So am I!” Susan said, which was also- well, you get the idea.
“Maybe you’re one of the people I was supposed to be keeping an eye on,” the other girl said, frowning. “But I think grandpapa would have mentioned you looking exactly like me.”
“Exactly,” Susan agreed, “except for the hair.” Her own short hair had proved both fashionable (in the 1960s) and practical, but she couldn’t help envying the other girl’s long braid.