Sienna Mercer grew up in Toronto, Canada. She was an only child, and always wanted a brother or sister – especially a twin. A twin would have been awesome! Sadly, she never got that sister so, when she was grown up, she did the next best thing - she wrote books about a girl who reminded her of herself, and gave her the most fun, fabulous twin she could think of!

Sienna began writing stories when she was a teenager, on a very wet day in Toronto when her cheerleading practice was cancelled - and she has not stopped writing since. She used to write in red leather notebooks while sat on her bed, but now does most of her writing in her attic, which is quite dark, and has some spooky cobwebs in the corners - the perfect location for thinking about vampires. She doesnt use red notebooks anymore, either, although she keeps them in a chest by her desk in the attic.

Sienna got the idea for My Sister the Vampire from a daydream she had - what if she had a super-cool twin sister... who was a vampire? She loved the characters - and their kooky friends and family - so much that she just had to keep writing about them.

When shes not daydreaming about vampires and cheerleading, Sienna enjoys travelling and exploring new cities, and keeps a detailed scrapbook of everywhere she’s visited. She lives in Toronto, kept company by Calypso and Angel – her two gorgeous cats. She is happily writing away and we wait for her upcoming books!