Here's a list below to help keep it all straight.
Bella (short for Isabella) to Beau (short for Beaufort)
The protagonist of the novel, Beau, is just as clumsy as Bella, is prone to being cold, gets himself into trouble and attracts many members of the opposite sex.
Edward to Edythe
Beau's love interest Edythe is small in size but very strong. She's sophisticated, mysterious, and often saves Beau from dangerous situations.
Jacob (or Jake) to Julie (or Jules)
Jules is friendly and open to Beau and has a natural, laid-back style. Her part in the love triangle doesn't grow in importance until the second book, which Meyer said she is currently not planning on writing for the gender-swapped version.
Dr. Carlisle to Dr. Carine
The vampire matriarch of the Cullen family
Esme to Earnest
The vampire patriarch of the Cullen family
Alice to Archie
Edythe's pretend brother and Jessamine's partner
Emmett to Eleanor
Edythe's pretend sister and Royal's partner
Rosalie to Royal
Jessamine's pretend brother and Eleanor's partner
Jasper to Jessamine
Archie's partner and Royal's pretend sister
Billy to Bonnie
Julie's mother and a good friend of Charlie, Beau's father.
Jessica to Jeremy
Beau's friend at the beginning of school
Angela to Allen
Beau's friend at school
Mike to McKayla
McKayla has a crush on Beau and asks him to the school dance.
Tyler to Taylor
Taylor almost accidentally hits Beau with her car, asks him to the school dance.
Lauren to Logan
Logan is rude to Beau and doesn't like him.
Eric to Erica
Erica has a crush on Beau, asks him to the school dance.
Rachel and Rebecca to Adam and Aaron
Julie's older brothers
Ben to Becca
Attends Beau's high school
Connor to Colleen
Attends Beau's high school
Lee to Leann
Attends Beau's high school
Samantha to Sean
Attends Beau's high school
Sam to Samantha (also known as Sam)
Julie's older friend
James to Joss
A vampire who attacks Beau
Victoria to Victor
Joss's vampire partner and friend
Laurent to Lauren
Victor and Joss' vampire friend