She is not insane just a little on edge and her personality is a bit on the bad side. Her mother and father died when she was about 6. As a child she had no idea what to do.

When Onyx was about 6 her parents were driving to an appointment they had. Onyx sat in the back seat of the car as they passed many other's. They continued to drive until they got lost and stopped on the side of the road. They did not know where they were going because they were going out of town to a better doctor.
Once they figured out where to go they had gotten back on the road. Onyx's mother had looked down for one minute as a semi-truck hit them. Her parents used the last of their magic to save her once they realised what had happened.
They were promptly escorted to the hospital but sadly died there.

When onyx's mother was a little girl her mother had been afraid of showing her the magic world. The magic world could be dangerous and corrupt her like it corrupted her sister. Onyx's aunt Crystal was exposed to magic at a young age along with Onyx's mom. Her aunt was so into magic she looked at forbidden book and other things intertwined with dark magic.
Once she was into all of the dark magic she tried so hard to fit in with the other's who practiced themselves. Whist Onyx's mother did what she considered correct. She went to Hogwarts,Played quidditch and had many other friend's and games. She had not known about anything util her sister was pronounced dead and was in casket with her a face so prune like it was almost as if her soul was sucked out.
Onyx's father however was not afraid to show her anything but agreed with his wife that it would be a good idea to do so. Once they had Onyx they removed anything/Packed away anything that had to do with magic leaving onyx with no clue of the magic world.

Karma and Oliver {Onyx's parents} Had no idea how to live amongst the muggles. The only way they could was to find a muggle to help them. Oliver's best friend was not a pureblood. He was a "Mudblood". The new parents always went to him when help was needed. Even lin's husband learned more about the muggle world and did things in it.

Eventually by the time onyx was 4 they were working in offices due to Oliver's friend and having her go over to her cousin lin's louse while they worked. C=They created a normal living setting just for her.

When she was first born [She is an only child] her parents did not want her exposed to the magic world. Once they passed away she went with her cousin. Her cousin was always different toward her then to her children. Her cousin had never took her to places or shared anything with her. On the other hand her children made sure she felt loved and appreciated.
Onyx was taken to a zoo with her 'family' and see was fascinated with the scaled animals. She always read about them when she was a little girl. Now that she is older she finally got to see one. She walked up to the snake exhibit and watches as it moved around. Her cousin however wasn't cruel just scared. Onyx's parents had told her that onyx is a wizard but did not tell the child.

~4 years ago~

Onyx was only 2 bit her parents had made sure to tell her cousin "Lin" that no matter what Onyx must not know she is a witch until she is old enough to go to hogwarts. Lin had understood what she meant but did not think that would die 4 years later leaving onyx in her hands. One of the reason she treated her differently was because the pureblood family she has WAS exposed to the magic world already.

She never knew about it until she got her letter. Her cousin was happy that she could finally let her know about the witching past. Her cousin however did let her go to regular school. She has made a lot of friends but one thing is for sure she found out she had magic there.
She was a very emotional girl. A girl who she hated made her cry. She was infuriated that this happened while she felt her ager rise she did not notice the glass in the bathroom mirror breaking. Once she did it was shattered.
She has the knowledge of a normal highschool girl. She was always quiet smart getting the Honor Role ad being in advanced classes as she is only in 6th grade. Now It is a matter of time before she learns when her professors have to say about her magic knowledge.