Katherine Elizabeth Shane was born to two of the worst parents she could have asked for as a little girl. Kedric Shane and Amelia Matthews, the two had a one-night stand and never even exchanged last names. Nine months later, Amelia have birth to twin babies, one boy and one girl. She kept the boy, but gave the girl to Kedric by dropping her off at his doorstep. Kedric had no idea as to who the mother was, he hooked up with several women around that time, and the note that was left with Katherine didn't help him figure it out.
Unfortunately for Katherine, Kedric's nefarious actions eventually caught up with him and he was convicted of threatening Charity Prince's life and attempted assault with a deadly weapon and thrown into Azkaban for two year, with the promise he could get an early release if he behaved. Well now Kedric had a reason to behave, so that's exactly what he did. One year later, Kedric was released into the real world. However, during that time Katherine had been staying at Lil Bundles, and the owner Rose Gilcrease wouldn't give Kedric his daughter until he proved himself. So, she offered him a job at Lil Bundles.
And Kedric more than proved himself, he was an excellent father to Katherine and was an excellent employee. He worked his ass off every single day, and eventually he caught the eye of a squib named Emily Hayden. She was the first mother figure that Kat had, and things were looking pretty good. Then Kedric screwed up, and screwed someone else too. He hooked up with Kimi November and knocked her up. That ended things between Kedric and Emily and left Katherine with Kimi as her mother figure, and she was not as good. Nine months later, Kimi had a daughter named Jasmine November-Shane. She stayed with Kimi and Kedric had Kat. Kedric and Kimi never really started dating before Kimi fled the coop, dumping Kedric with Jasmine. Now Kat had a sister.
For about a year things continued with Kedric parenting both girls by himself, then his world turned upside down when an old friend/love interest turned up. Mississippi Ashford, it didn't take long for the old chemistry to flare up and the two hooked up. However, this time they started dating. Eventually, one thing led to another and Mississippi wound up pregnant. Then three months before Katherine's fifth birthday, Mississippi had identical twins named Elina and Laila.
Now Katherine had a proper family, and that turned out to be a good thing for her. She was a pretty fantastic big sister, in fact her first magical sign came when Elina fell down when learning to walk and got a cut on her head. Katherine was the only one around at the time and was worried for her baby sister, so she just made the cut go away. Kedric and Mississippi could not have been more proud of Kat. That mere fact made Kat want to help her little sisters in any way she could.
For the next five years that's how things worked in the house. Kat was the best big sister Jasmine, Elina and Laila could hope for. She loved and adored them and was always willing to help them in any way she could, whether that was advice, homework help, sticking up for them against nasty kids at the orphanage. Whatever. Katherine was there for them, but she also knew when to back off. Usually. Unless she was really worried, then there's no force on earth to stop her. And this kind of behavior wasn't just limited to her sisters, but all the kids who may be younger than her at the orphanage. She took them all under her wing and became their big sister.
Katherine is now 11 years old and is preparing for her first year at Hogwarts.