Early Life
Sophie was the second born child of the Yasshou Clan's head. Her older brother, Charlie was 2 years older than her. The clan had been the creators and teachers of the Lineal Sword Style for many generations. They lived on a decently sized island in the West Blue called Oshim; where the clan was well respected and had places of leadership in the largest villages. As a child of the main clan, Sophie was expected to be a great warrior and continue the style.
While a disappointment at first due to preferring to do other things, she eventually started training and taking it seriously after a long talk with her father. He explained that as long as she used the style, nobody could then say anything about her doing other things as well; he wanted her to be happy and do the things she loved. Due to her very young age she mostly trained her body with training tools designed as toys and wooden swords. Charlie was much more into training but was sometimes a bit overzealous and tried to do things he wasn't ready for etc, even trying to get her to join in sometimes. During this time her parents had two other children, her brother Harry and sister Wendy; he was around 2 years younger than Sophie while she was around 3 and a half years younger. She trained with a few other kids but most people who came to the island to learn were adults so she didnt interact with too many people aside from her siblings and father until later on.
After noticing her eye for detail and interest in learning about the world, her mother started teaching her how to write/read different languages, how to manage money and other resources effectively and various other things. While she didn't understand all of it, she enjoyed learning about it and managed to somehow fit everything into a somewhat manageable schedule.
Adolescence
Until she was 12 life was pretty much the same most days, wake up and do morning stretches/exercises then have breakfast. Do some training drills, with or without a sword. Work on a subject that her mother has been teaching her. Practice/revise other topics so she doesn't forget then have dinner. Spar with her father or Charlie. Do some more drills. Clean or do other chores. Free time for a few hours then have evening meal. Work on a subject or revise or practice with a sword. Free time and/or family time and then bed.
Sophie didn't spend much time in the actual dojo or practicing with others but Charlie did. They were quite close until one day after going and being with their father all day, he grew distant and spent his entire time training; even doing it way into the night. Both him and her father wouldn't say why or where they went. By this time Harry was well into learning the style and training too so she just started sparring with him instead of Charlie. Her father started to spend a bit more time with her as well, not just when training but during her free time as well.
A few months after Charlie became distant, a group of pirates came to the island. Her father greeted them and found out they weren't there to pillage, they had learned about the clan and the sword style and several of them wanted to learn. After testing them, many were found unworthy and denied training. This caused the captain to order his men to attack, but there was too many warriors for that to be successful. Sophie mostly protected Harry and Wendy rather than fought. After defeating them and putting them in chains, her father now had to decide what to do with them. A lengthy discussion followed with Sophie being nearby talking to some of the people who fought the pirates. A shout got everyone's attention, Charlie had tried to execute them but their father had stopped him.
A group of marines eventually came to take them away. Despite many wanting him to be banished for going against the head of the clan, he was only lightly punished and had to be near his father or a senior warrior at all times for a while. A week or so after, Charlie came to speak to her; the first proper conversation since before that day. He still wouldn't talk about it but he talked about other things such as father isn't fit for leadership and how he wishes to leave to explore the world. At first she tried talking him out of these things but overtime she gave up as she could see how much he had changed and realized he wouldn't change his mind. The incident brought multiple people to come to the island, some just for somewhere safe to life and others to join the clan and start training. Among them was a tall man called Vara who already had some skill in swordmanship, he became a good friend of Sophie's over the next couple of years.
Several nights she thought she heard moving and someone sneaking about the house but was never able to find anyone. Others reported similar things but nothing was ever found even after it persisted for quite some time. Charlie wasn't as distant anymore but still didn't see eye to eye with their father, ignored their mother trying to help and spent no time with their younger siblings; as he was still too busy training. Sparring with him was like actual combat, he only showed concern if she took a really big hit or just when he won; as she stood no chance against all the training he did. Aside from these few changes, her life remained relatively unchanged for over 2 years.
At 17 she was already a warrior of the clan, but wasn't allowed to join in with some things such as big meetings or certain 'high level; training. Sophie didnt mind to much as she was still happier doing other things, her mother had run out of things to teach her so had got various people from the clan and settlements to teach her instead. Harry was very into training and being a warrior but also liked cooking and several other activities, while Wendy was a bit more like Sophie; only doing it because she had to. Vara was now a senior warrior but spent time doing more than just clan stuff, helping to build, fix things or just generally help where he could. The clan and island was prospering and had both grown quite a bit, the clan's main home was now a very large town with a port; allowing it to start seeing trade from other islands.
One day she was awoken early by her father and was told to follow him. He took her to a part of the dojo she had never been, under it; having to pass through a large door with a symbol on it. Once they had gone past several rooms he stopped at the one right at back that had the same symbol on it. He then told her the truth about the clan and sword style, they channeled the power and spirit of all who came before them; creating a link that got stronger each generation. They could also use this 'link' to empower their body and techniques and perform various feats; but it could also backfire and come at a cost if not treated with respect or used without caution etc. Its why they test people and why they wait so long to fully explain. Many people know that its not a normal style of swordmanship, but its hard to prove and can be explained in various other ways.
Shocked and feeling kind of annoyed that he didn't tell her anything, Sophie asked if this was why Charlie changed. She didn't get a straight answer so guessed there was more to it than just this. Due to how far she had already come, she had the choice to continue or not; and he would have most likely told her even if she had quit before coming this far. Deciding to not continue, she went back to the same lifestyle although with slightly less sword training; very happy with how her life was going and where it might lead. And that's when it all came down around her.
A while after she was told, a big group of ships came towards the island. Thinking they might be pirates, her father had them prepare just in case; but it was actually the World Government. Relaxing and greeting them, the person in charge and others ended up in a meeting with the senior warriors and the clan head. Most of the people on the ships were not Marines but instead members of Cipher Pol. Sophie went about her day normally but ended up near where the meeting was after a while. Cipher Pol knew about the special nature and wanted to teach it to enhance their agents and later on general Marines. Once it was obvious he wasn't going to say yes for many reasons, they threatened him and basically gave an ultimatum, teach or be destroyed; as it was deemed too dangerous unless it was under their control. Her father still said no.
The agents not in the meeting went from being polite and normal to attacking and destroying in a matter of seconds, their superiors using a den den mushi after surrounding the clan leader. The Yasshou Clan and the other inhabitants fought back, with Sophie also joining in but was also looking for siblings and parents. She found Charlie working his way to their house to get their mother so she helped him out, but it was too late; the agents had already been there and killed everyone. Going into a rage at seeing his mother's body, Charlie ruthlessly attacked any enemies nearby and headed towards the meeting hall. Sophie eventually pulled herself together after crying, as she knew she had to find Harry and Wendy. Although not as powerful as some of the higher agents, she was easily able to take on most of them or create an opening to escape. Making her way to the main area, she eventually found Harry trying to protect Wendy with the help of several injured warriors.
She quickly made her way towards them until she realized who they were fighting. Vara was now wearing a suit like the other agents and killed one of the warriors as she watched, too stunned to move. Screaming "Why" at him, Sophie joined the fight but was quickly overwhelmed; several Shigans made her right arm useless and he then all killed the other warriors still fighting. He explained he was never a part of the clan, he was a spy sent to find out about the sword style and then report whether they should destroy it or not. Harry tried attacking him to save her but he used a Shigan reflexively and hit him in the chest. Seeing he had killed a kid without meaning to, Vara ran off leaving her and Wendy to their grief.
A senior warrior called Welik found them and managed to bring them to the coast, a small boat was waiting with several other people inside; including some other clan members. As they got on and started to sail away, Charlie reached the shore not far down, with their father. They wasn't fighting agents, they were fighting eachother and arguing; Sophie was too far away to make much out. She tried to turn the boat around but the warriors knew they couldn't. As they drift out to sea, the last thing she sees is Charlie stabbing him in the chest.
Adult Life
With the other clan members, they are somehow able to survive but eventually a bounty is placed on Sophie and many of the other warriors heads; making it harder due to the bounty hunters and Marines now being after them. During one incident in a small town, several of the others are killed trying to protect her and Wendy; as they are now the highest ranking clan members due to being children of the leader. One of the warriors manages to become a bounty hunter and sends money to them, but it slowly became less successful due to him having to travel further and they couldn't stay too long in one place. He eventually stops hunting and comes back to help more directly.
Overtime Sophie manages to gather some information about an organisation that's against the World Government, but due to its secrecy isn't able to find out how to find them or anything else that might help. Having basically exhausted most 'safe' places in the West Blue and feeling like they would be easier to find outside of the Four Blues, her group gathers up some money and manage to pay some pirates to bring them with them when they go to the Grand Line. Predictably once they are in it they try and kill them and take their stuff, but are no match for Sophie and the other warriors; she had started training again and was nearly as good as Welik, the only senior warrior in the group. She couldn't use any of the high ranking techniques or ones involving channeling ancestors etc. but was still a very powerful swordsman.
A year or so after coming to the Grandline they encounter the Revolutionary Army completely by chance and help to liberate an island from tyranny. After explaining who they were and why they wanted to find them, they are allowed to join as preliminaries members until they prove themselves. Sophie manages to convince them that Wendy would be in danger if she went so they get some people to look after her; plus two warriors from her group stay with her as well. The Revolutionaries was infiltrating a Marine base to get some information while another group caused a distraction on the other side of town. Although at first the other warriors still focused on protecting her, Sophie orders them to treat her like any other member, explaining that they were no longer Yasshou Clan members as they were now Revolutionary agents and she was no longer their leader. Proving themselves during the mission, they were taken to a local base and fully inducted. Despite initial concerns, the warriors eventually went on separate missions and split up. Wendy became a helper at the base while Sophie went on missions and gained several accolades and commendations due to her vast knowledge and skills in many areas.
It was on one of these mission which involved going to a World Government lab she met the former Marine and Dwarf, Jade Belle. After being split up from the other agents by enemy forces, the two headed to the objective only to find it was a trap, all the doors locking and numerous advanced robots attacking them. Working as an amazing team, Jade was able to get into them one by one to disable them while Sophie defended her from the others; as the robots were too strong and too many to destroy normally. She was injured but kept fighting till she could no longer stand; luckily this gave enough time for the others to regroup and get a door open and start helping them. After explaining it was a trap, Jade carried her back to the ship herself. Both of them were promoted for managing to do something that even the entire group would have struggled with, plus their previous separate achievements.
Some time after that and being in the same mission/groups a few more times, Jade came to find her after she became an officer. She wanted Sophie to be her second in command which she instantly said yes to. They have been on several missions and helped liberate multiple countries from the corrupt World Government. More recently she found out Charlie had joined a pirate crew as she saw his wanted poster.