TL;DR: Wednesday Addams but with Problems
Jo grew up knowing she was a pureblood heir and as such has never faced the consequences of some of her brasher actions the way others might have. Jo has a confidence to her that makes her think that her ideas are always good (mixed results). She wasn’t raised to believe in pureblood ideologies (maybe more accurately, she resisted learning to believe in pureblood ideologies). Still, there is an air of snootiness about her, and she gives off the impression of being BOTH an insufferable know it all AND a force of chaos who flaunts rules because she knows she won’t suffer the consequences of her actions.
Alice has expected the most from Jo, and Jo has grown up to make sure that she is perfect. The drive for Alice's version of perfection has, in many ways, made Jo into a mini-Alice. She is strict, demanding, and vindictive. Her sense of humor skews dark, and she's got a sharp tongue that will very likely get her into trouble.
Jo doesn’t know it yet, but she is struggling with coming to terms with who she is and who she wants to be outside of her parent’s influence. Being out of Alice's (and to a lesser extent, Matt's) shadows will help Jo grow into a capable witch--and, if all goes well, maybe even a likable one, too.
Jo looks like her mother: striking features, dark hair pulled back for the sake of efficiency, and well put together. Jo doesn’t leave her room looking anything other than her best. The only thing that she inherited from her father is his eyes: a lovely shade of green that her mother says is her best feature.
Alice Archer nee Beastly and Matt Archer had a child a little under nine months after getting married. Jo was their first born, and they later had twins. Their marriage wasn’t a normal one, but Jo always believed that her parents loved each other.
Her home life could be called eccentric at best. Alice and Matt had separate rooms. Matt was a very hands on, loving parent and doted on his children. He was the more maternal parent and all his children knew to go to him if they were afraid of getting in trouble. Alice expected a lot from her children. She was never cold, per say, but had trouble verbally expressing her feelings to her children. Alice was strict and being a mother always came second to her. However, this distance didn’t mean she loved them less; she was always very protective of her children and taught them self defense as soon as she could.
Alice expects a lot from Jo given her status as first born.
THE INCIDENT (she will not reveal what this to anyone who asks and only refers to this event as The Incident):
While shopping for school supplies, her parents realized that they each thought she was going to a different school; Matt believed she would go to RMI to uphold family traditions, while Alice believed her daughter would be sent to Hogwarts. Due to the power imbalance of her parent’s marriage, Jo had assumed her mother would have her way and that her father would eventually cave to her Alice’s demands. For the first time, Matt held his ground. Their miscommunication rapidly shifted into loud, volatile communication, and they left Wizard Target™ separately. Jo went with her father in a bid to escape Alice’s wrathful soap-boxing about trophy husband rights, and as a result, was promptly enrolled into RMI to start school two days later.
After her parents’ messy, public divorce, Jo found herself in a school of strangers. Now, Jo finds herself in a place she never expected to be, surrounded by people she never expected to meet, and needs to decide what path she will follow moving forward.