In the first Supergirl fanfiction, we see Maggie and her new partner, Kara.Maggie is very wary of her new partner due to her physical appearance, but she soon finds that Kara is much more than she bargained for.
In this story, we see how Kara deals with more struggles, including people finding out that she is Supergirl. Without giving too much away, just know that this story is somewhat depressing, but it does have some nice moments.
Though the main character of this story is Oliver Queen, we still get a large amount of Supergirl action. This story covers just about every character in the Arrowverse, so there are many great moments with so many unique groupings of characters.