Well, if Lucy got run over by a car in fanfiction, it might change the whole dynamic of the Fairy Tail group. Gray might become more withdrawn as he's not great at dealing with such emotional turmoil at first. Erza would immediately take charge, trying to organize help for Lucy. And Lucy herself could have some sort of near - death experience that gives her new magical abilities or insights. Maybe she could even communicate with spirits in a different way after such a traumatic event.
In fanfiction, if Lucy were run over by a car, it could lead to a very dark and angsty storyline. Her friends in Fairy Tail would be devastated. Natsu, for example, would likely go into a rage and vow to find out who was responsible. The guild would probably come together to support her, and there could be a search for a way to heal her, perhaps using magic that they have to discover or learn. It would be a major turning point in the fan - made narrative.