Really, Hudson and Charlotte Summers weren't interested in having a child, but what else does a married couple do? Besides cheat on eachother relentlessly, of course. So they did their marital duty or whatever and had a kid, and honestly if she hadn't been so damn loud and needy they probably would have forgotten about her.
So...Tori's parents weren't great. They made sure she didn't starve and that she got to school and that she didn't die but they never bothered spending much time with her and really never paid her much attention. Her father came from old money and her mother was an anesthesiologist so if she needed something they told the nanny to do whatever and, later, pretty much gave Tori free reign. Honestly, for the sheer lack of shits they gave, it's a miracle she grew up to be so down-to-earth.
Tori did well in school, academically, but she was small and shy and an easy target for the mean kids at school. Her parents didn't do anything about it, even when she came home crying, so she decided to make like in the movies, steal a credit card, and sign herself up for martial arts classes. Not that she ever really used them much, but she did very well in her martial arts class, and several of the means kids happened to be in her class, and they weren't so mean anymore once they figured out she could kick their mean little asses.
Tori's parents moved them up to Washington, DC when she was ten, and put her into a private muggle school. There she met Max Grey, and the two became fast friends. Tori's first sign of magic didn't actually come until she was eleven - she and Max were playing in a tree from which, of course, Max fell out of, cutting her arm pretty badly on her way down. The amount of blood worried Tori a lot and the tried to cover it with her hands to stop the bleeding, and then there was a small flash of light and suddenly the bleeding was...all but stopped. Max was very excited and seemed to know what was going on, meanwhile Tori was just mostly confused. Max ran to get her mom who explained it pretty well to Tori - about the magic and all that - and said she would get in touch with people to inform her parents.
Her parents, unsurprisingly, didn't care all too much. They were surprised at first, but after that...it was whatever. Sarah Grey was sending her daughter to this...Salem Institute, and she was a sensible woman, so they really saw no problem with it.
Tori enjoyed Salem. Her best friend was there with her, and the magical environment, while different, was nice to be in. Tori enjoyed Transfiguration most, enjoyed the challenge of it, and later her enjoyment of the subject helped greatly with her Healing courses. She wasn't popular at school, but she was on good terms with almost all her classmates and she was always ready to help someone out if they needed it.
In their fifth year, Max left suddenly, without so much as a goodbye or even a letter. Tori felt like part of her life was missing, really; she and Max were so close that her absence was almost tangible. For the longest she had no idea what had happened and she was very upset about it. Her grades suffered a bit as well since she wasn't able to get in touch with Max's mom either, which was downright odd, but her DADA teacher finally let her know they'd moved to Britain.
Over the summer before her final year of school, Tori's family moved again, this time to Britain since her mother had accepted a position at a British hospital. Tori didn't mind it too much; she had friends at Salem but she wasn't terribly close with any of them, and she'd heard that Hogwarts was a great school and that it had a good healing program.
At Hogwarts, she was sorted into Gryffindor, which really wasn't too surprising, even if she did prefer Ravenclaw's colors. She reconnected with Max that year, and after a nice, long chat they essentially picked up where they left off. That being, of course, that they were both very gay for eachother.
Tori graduated with high scores on all her NEWTs, married Max very soon after graduation, and started work as an intern at St. Mungo's. She loved her job at Mungo's, and loved it even more when she was promoted to full healer. She worked in creature-induced injuries, and it was always fun to see what kind of bullshit people got themselves into. She learned a lot about antidotes and antivenoms and became very skilled with her potions in that position.
On December 6, 2026, Tori turned herself in for the murder of Lydiae Bardy. After a stint of time in the holding cells at the Ministry and a visit to the UK from her old psychiatrist, she was moved to the psych ward at St. Mungo's, where she stayed until October 23, 2029. During her stay at St. Mungo's, it was determined that she had dissociative identity disorder, for which she was treated for quite well. During the course of her treatment, she all but cut off contact with her wife and barely kept in touch with her daughter - most of their communications went through her mother-in-law, who was the only person besides hospital employees that she saw regularly. When she was finally discharged, part of her discharge interview involved her listing the sort of situations she would be actively avoiding for her own health, and one such situation was becoming so attached to someone that she couldn't stand not being the center of their world, so...after she was free and clear, she got a divorce.
After eleven years of marriage - or eight, discounting the time she spent in the hospital - it was weird being on her own. And it wasn't that she had any hard feelings against Max. They were great together, and she still loved her very much, but they both had their own issues that they needed to take care of, and neither of them were getting very far when they were both using eachother as a crutch.
She wanted to travel, so...she sold everything she didn't need, packed the rest into a few bags with some good undetectable extension charms on them, and fcked off across Europe and Asia, taking about a year to make her way across the continents. Eventually she made it to Japan where she was able to stay with an old friend from Salem that she'd kept in touch with, and she found work at a magical hospital in Osaka, where she's worked for the last eight years.
In Japan, she worked with a new therapist who didn't think she actually had DID - she thought Tori was affected by some sort of spirit or demon instead. Tori thought she was nuts initially, but as they discussed it more, it started to make sense. Her therapist persuaded her to visit a Seer to help them figure out what might be affecting her, and they discovered it was actually an ornate leather-and-steel bracelet Tori had worn since she was eight. Her father enjoyed his antiques, and he gifted her the old but well-preserved bracelet for her birthday. Tori had worn it almost constantly since then; at the time, the bracelet meant the world to her. Her mental state - that is, she often felt lonely and worthless and rather resentful at times as well - made her susceptible to the bit of soul inside the horcrux. Gladly she turned the piece in to the Japanese Ministry and after she did, it felt like a great weight she'd grown accustomed to had been removed from her chest.
She's decided to move back to Britain mostly out of spite. The British Minister pisses her off and Britain did kind of become her home so she feels partially obligated to stubbornly take up a bit of gay space in it.