There's a fanfic called 'Wounded and Yearning'. Harry is seriously hurt in a skirmish. His longing for Ginny becomes his strength. Ginny, sensing his need, rushes to his side. The story beautifully portrays their relationship as she helps him through his physical and emotional pain.
Jealousy could be a reason. If Ginny sees Harry getting too close to another female character, she might lash out and hurt him with her words. For instance, if Hermione and Harry were spending a lot of time together on a project, Ginny might feel left out and say something mean.
Ginny's reaction could also involve a sense of helplessness at first. But then she'd quickly gather herself and use her resources. For instance, she might call on her friends and family for help. She'd be by Harry's side constantly, using her presence to comfort him and also using her knowledge of magic to try and ease his pain.
One great 'Ginny Wants Harry Back' fanfiction is 'Rediscovering Love' on FanFiction.net. It shows Ginny's journey to win Harry back after a big misunderstanding. The author does a great job of capturing Ginny's determination and Harry's inner turmoil.
In many such fanfictions, Ginny might immediately rush to Harry's side. She could be extremely worried and determined to help him get better. Maybe she uses her magic skills to heal him or just stays by his side to offer emotional support.
Another theme is redemption. Ginny tries to redeem herself in Harry's eyes. She might change things about herself that she thinks contributed to their separation. For instance, she could become more understanding or less impulsive.
One common theme is the exploration of their relationship. It might show Ginny's deepening feelings for Harry and how she tries to get closer to him. For instance, in some stories, Ginny might be shown as being very protective of Harry during difficult times at Hogwarts.
It could be a rival from another house. For example, a jealous Slytherin who wants to take Ginny out of the Quidditch game. They might use some underhanded tactics to make her broom malfunction and cause her to get hurt.
It could imply that in the fanfiction story, Ginny desires Harry to be a significant part of her world within the narrative. Maybe she wants him to be involved in her adventures, her personal growth, or her relationships as depicted in the fan - created story.
Another reason might be miscommunication. Harry has a lot on his plate, and sometimes he might not express himself clearly. He could say something that Ginny misinterprets as hurtful, when in fact he didn't mean it that way at all. For instance, he might make a comment about her Quidditch skills that she takes the wrong way.