Well, Logan Laura has a rather tragic origin. She is a clone, made from Wolverine's genetic material. The people who created her had no regard for her as a person. They just wanted to make use of her abilities. Growing up, she faced a lot of hardships and was forced to fight and kill. Her origin story is a story of survival against all odds. She had to break free from the control of those who made her and find her own identity.
One key element is the use of Logan's DNA. It's the basis for her existence. Another is the fact that she was created as a weapon. And the cruel training she endured from a young age is also important.
Without more context about 'Laura Black Story', it's impossible to say exactly who Laura Black is. She might be a symbol of something in the story, like hope or perseverance, or simply a character with a unique personality and backstory.
One main challenge was probably her physical mobility. With 600 pounds, simple things like walking or getting up from a chair would be very difficult. Another could be her diet. Changing eating habits that led to such a large weight would be tough.