Yes, there are quite a few. You can start by looking on fanfiction.net or Archive of Our Own. There, you'll find various stories exploring the idea of Harry looking like Sirius, some might focus on how it affects their relationship in the wizarding world, or how it plays into the overall plot of the Harry Potter universe.
Fanfiction.net is a great place to start. It has a large collection of Harry Potter fanfictions, and you can use the search function to look for stories specifically about Harry looking like Sirius.
One popular fanfiction with Fem Harry looking like Lily could be 'A New Destiny'. It has an interesting plot where Fem Harry's resemblance to Lily plays a significant role in the wizarding world's perception of her. Another could be 'The Lily - like Harry', which delves deep into how this resemblance affects her relationships with other characters, like Snape who had a complex relationship with Lily.
It could be offensive depending on how it's meant. If it's said with a dismissive or negative connotation towards the idea of black - influenced interpretations or fanfiction in general, then it's offensive. Fanfiction is a creative outlet, and black - centric interpretations can add new and valuable perspectives.
Well, if fem Harry looks like Lily, it might lead to all sorts of new plot developments. It could influence how she's treated by certain characters who knew Lily, or even give her some of Lily's personality traits.
One reason could be Harry's impulsiveness. Harry often jumps into dangerous situations without thinking, and Sirius, being his godfather and having a protective nature, would shout at him to make him realize the risks. For instance, if Harry decides to go after a Death Eater alone.
He could be more defiant towards the authority figures he doesn't trust. Sirius was always a bit of a rebel against the Ministry when they were wrong. So Harry might openly question the decisions of some of the Hogwarts teachers or the Ministry officials who visit the school, if he feels they are being unjust, much like Sirius would have.
One key element is the impact on other characters. For example, characters who knew Lily, like Snape or Dumbledore, would have complex reactions. Snape might see Fem Harry as a reminder of his unrequited love for Lily. Another element is how Fem Harry herself deals with this resemblance. Does she use it to her advantage? Or does it make her feel pressured? Also, the plot might involve how this likeness affects her place in the wizarding world, whether it gives her special treatment or makes her a target.
The theme of mystery often comes up. Why does Harry look so much like Lily? Some fanfictions explore this as a mystery that needs to be unraveled. It could be related to some long - forgotten magic or a prophecy. There's also the theme of love. Characters who loved Lily might transfer some of that love to Harry because of his appearance, which then creates complex emotional dynamics in the story.