I'm not entirely sure what specific 'yarn', 'stories' and 'bruises' are being referred to here. It could be a story about a knitting project (yarn) that had some mishaps (bruises) and all the tales associated with it. But without more context, it's hard to tell the full story.
Bruises have a rather interesting full story. They can happen in various ways. Maybe you're in a hurry and accidentally walk into a doorframe. This sudden impact can damage the blood vessels just beneath your skin. The body's immediate response is to try and contain the damage. The leaked blood starts to clot, which is why the bruise initially looks like a red or purple mark. As time passes, the body reabsorbs the blood components. The hemoglobin in the red blood cells breaks down, which is what causes the color changes in the bruise over time. It's a complex yet common physiological process that shows how the body deals with minor traumas like those that cause bruises.
Another reason might be related to his home situation. Although it's not as prominent in the fanfiction's context perhaps, in the original story, the Dursleys were not kind to Harry. If this aspect is incorporated into the fanfiction, it could be that he got the bruises from their mistreatment before coming to Hogwarts.
I'm not sure specifically as I haven't read it. But generally, a fanfic with such a title might be about a character who has bruises that for some reason don't go away. It could be related to a mystery, a medical condition in a fictional world, or perhaps some sort of ongoing abuse or struggle that the character is facing.
I don't really know what 'yarn bruises' means exactly. It could be something unique to a specific type of yarn - related activity. Maybe it's about the marks left on yarn when it's dyed in a certain way that gives the appearance of bruises.
I'm not entirely sure specifically what 'yarn bruises' refers to. It could potentially be about bruises that occur when working with yarn, perhaps from a knitting or crocheting accident. Maybe the yarn is rough and causes abrasions on the skin while handling it, leading to what could be called 'yarn bruises'.
I'm not entirely sure specifically what the 'full story' regarding bruises and yarn would be. It could be a very creative or personal story. Maybe someone got bruised while working with yarn, like they tripped over a ball of yarn and got a bruise. Or perhaps there's a story where yarn is used to represent something in a story about bruises, like using different colored yarn to mark where bruises are on a body in a medical or artistic context.
A young woman named Lily started getting bruises on her legs. She lived alone in an old apartment. One day, she found a hidden room in her apartment. Inside, there were pictures of people with bruises all over them. As she looked closer, she saw that the bruises seemed to form a pattern. That night, she woke up to a cold touch on her leg and more bruises appeared. She soon discovered that the apartment was built on an ancient burial ground and the spirits were marking her as their own.
Maybe it's the work of a cursed object. A person could pick up an old amulet or something similar in an antique store. Once they have it, an evil force associated with the object starts to inflict bruises on them, slowly draining their life force as the bruises spread.