Kirako, a Hexblade Warlock of mine. This is a long one.
Originating from a distant and foreign land, Kirako came from a family made very well-off by their ancestors, powerful warriors that obediently served the lords of the lands until they came to positions of power and wealth themselves.
By the time Kirako was born, the youngest in a family of five daughters and no sons, her family had long sworn of the ways of the blade, for there was no longer any need for it in the era of peace that they found themselves in.
Kirako was raised to be adept in the ways of art, which she was very passionate about. She learned poetry, calligraphy, painting, anything she could receive lessons on. At times, her mother insisted on her marrying to continue the family lineage, but she always got away with the excuse that she had sisters, so she didn't need to marry or have kids, allowing her to continue her artistic pursuits.
But one day, her life of solely artistic pursuits came to an end.
It all started when a gang of thugs attempted to rob and possibly kill Kirako's family. Her father put up a good fight, but he was no warrior. He had never been in a real battle, nobody in her family had. He fell, and in a panic, Kirako moved to save her family. She disappeared into a shrine in the house, and felt called to a particular item.
An old sword. A blade used by her most famous ancestor, legendary and with the sheath still stained with blood that nobody could wash away. She had always felt an odd calling to this room, much of her art was inspired by the many old belongings of her ancestors collected and put on display in this room. But the blade was one she could never take her eyes off of. She recalled the tales her mother told her, of its legendary power, giving even untrained men great brute strength and skill.
She grabbed it, unsheathed and felt something take hold inside of her. As she ran back to her family, time seemed to slow. She heard a voice come from within the sword that she so desperately gripped with whitened knuckles. Some kind of Yokai, a demon, perhaps even an Oni. It offered her the power to slay those who opposed her, for a price, a deal. She agreed. To this day she doesn't remember the details of the deal, for the adrenaline and panic made her quick to accept.
Time suddenly flowed normally for her again, and she was still running. She saw her mortally wounded father on the floor, and her mother trying to protect her sisters some way, somehow. One of the thugs struck her mother and everything went red.
Every cut against flesh caused the sword to wreathe itself with more and more blood. Power surged through her. When she was done, she found mutilated corpses scattered across the floor, and a terrified family hiding in another room. She was clean of blood, but her blade was not.
With the help of one of her sisters, he mother was able to recover from whatever injuries she had sustained. But her father was too worse for wear, and he passed on the same morning, though not before warning Kirako that the blood she shed that night was only the beginning, for the thirsting blade she now held would only ever demand more.
Kirako tried to ignore this advice for a time, but some week or two after that fated night, after she had fully mourned the passing of her father, she felt the calling of the blade again. She tried to ignore it, but when she awakened one morning, she found it unsheathed beside her. It demanded sacrifice, more bloodshed. She continued to ignore it, but the longer she tried, the more intrusive it became.
It appeared beside her when she wasn't looking regularly. It filled her mind with thoughts and urges of violence. And it was indiscriminate. Guests, travelers, people she passed by on the street. Even her mother and sisters were surrounded by thoughts of violence, to the point she could no longer look at any of them without imagining their bodies, drained of blood.
Eventually, after catching herself genuinely considering the urges she the blade forced upon her mind, she decided enough was enough. She packed up, got ready to leave. She hid the true reason for her leaving from her family, framing the reason she was leaving as an "artist's journey", not wanting them to know the truth. They helped her prepare and soon enough, she bid them farewell, and set off to travel far, far away.
She became an adventurer. A new and inexperienced one, sure, but she felt confident that the blade would keep her safe, even if it was the reason for all her turmoil.
And so she wandered. Traveling, shedding blood for money, eventually finding herself in distant lands, ones with much more conflict, where she could much more easily find people to kill. Where the services she could provide with her blade were sought out much more.
But at the same time, she used the lands she found herself in as new artistic inspiration. She had not given up that passion, after all. After long battles, or on days of peace, when the blade's thirst for blood was temporarily quenched, she found herself able to sit down and quietly create something new. A new poem, a new painting, or even just practice her calligraphy. She sometimes sold what she made, but most of the time, the art was for her.