This is a rewrite, the original had the twins together and raised by the Cullens, and it was a crossover between Twilight and Teen Wolf, but I chose to change it to make it easier.
Two five year old twins runs for their lives away from their abusive home.
Mackara and Zephyr Harper, the two children getting separated, Mackara landing herself in Forks, meanwhile, Zephyr disappearing completely, presumed dead by his sister, Mack being found by a husband and wife, alongside their own 5 year old daughter.
The two girls growing close as Mack and her brother once were.
Then Mack's new parent's divorce and her mother takes her and her new sister away to Phoenix, the girls grow up as close as ever, her sister keeping Mack's biggest secret, in turn Mack uses this secret to protect Bella against anything and everything.
when they reach 17, they move back down to forks with their dad, only to find that Mack's secret, isn't the only one that to be revealed.