Hermione knew Ginny's history, though certainly not all of it. Being possessed by the greatest Dark wizard that had ever been born didn't leave the witch unscathed. Ginny sought out danger even when they were still in school. Not nearly as much as her older brother and his two closest friends did, of course, but she was hardly some innocent virgin afraid of the Dark. She'd been consumed by evil when she was young. Was it really any surprise that she would keep looking for it wherever she could find it? Truthfully, it always amazed Hermione that Ginny didn't become a Death Eater. She seemed like a much more likely candidate than even Hermione herself.